CVE-2026-89563

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-89563", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.725Z", "datePublished": "2026-09-11T19:44:34.375Z", "dateUpdated": "2026-10-19T08:48:56.784Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:48:56.784Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nip6_tunnel: use skb_cow_head() in ip6_tnl_xmit()\n\nip6_tnl_xmit() may need to expand headroom before it can push the\nouter IPv6 and optional encap headers. It currently does that with\nskb_realloc_headroom(), copies skb->sk ownership, consumes the original\nskb, and then continues processing with the replacement skb kept only in\nits local variable.\n\nThat is safe only if the helper cannot fail afterwards. But this helper\nstill has post-reallocation error exits. collect_md tunnels reject\nnon-NONE encap after the replacement, and ip6_tnl_encap() can also fail\nlater. In those cases the helper returns an error to its callers while\nthe caller still only has the original skb pointer.\n\nBoth ip6_tnl_start_xmit() and the IPv6 GRE paths free the caller skb on\nerror, so they can end up freeing an skb that ip6_tnl_xmit() already\nconsumed.\n\nUse skb_cow_head() instead. It provides the required headroom and\nwritability without privately replacing the caller-owned skb, so later\nerror returns cannot leave callers with a stale pointer.\n\nThe Ethernet users, ip6gretap and ip6erspan, clear IFF_TX_SKB_SHARING\nand already call skb_cow_head() before entering ip6_tnl_xmit(). They do\nnot rely on the removed skb_shared() reallocation. This also makes the\nIPv6 tunnel path consistent with ip_tunnel_xmit()."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:L - The double-free is in ip6_tnl_xmit() on the ip6tnl/ip6gre transmit path. The reliable trigger is local: create a collect-metadata tunnel with FOU/GUE encap via rtnetlink, then push a packet through ip6_tnl_start_xmit() with tc tunnel_key+mirred. Ordinary remote packets on a working ip6tnl do not hit the post-realloc error path.\nAC:L - Once the collect-md device is created with non-NONE encap, any skb that needs headroom expansion takes skb_realloc_headroom(), consume_skb()s the original, then deterministically fails the collect_md/encap check so the caller kfree_skb()s the stale pointer. The published PoC reproduces this without a race or lucky layout.\nPR:L - Creating ip6tnl/ip6gre and tc filters needs CAP_NET_ADMIN, which an unprivileged user gets in their own user and network namespaces (unshare -Urn). The reporter confirmed this userns path; the resulting skb double-free is not confined to that namespace.\nUI:N - The attacker creates the tunnel, installs the tc redirect, and generates the packet themselves. No other user must mount a filesystem, open a file, or otherwise interact.\nS:U - The skb double-free corrupts kernel heap (skbuff_head_cache) on the same host. This is standard in-kernel memory corruption, not a VM escape, IOMMU/DMA bypass, or other cross-authority impact.\nC:H - consume_skb() frees the original skb and the caller later kfree_skb()s that stale pointer, a slab use-after-free/double-free. Reclaiming the skbuff_head_cache object yields an arbitrary kernel read primitive, so confidentiality impact is High.\nI:H - The same skb double-free/UAF is a heap primitive: the freed sk_buff can be sprayed and the second free or a later dereference used for an arbitrary write or control-flow hijack, so integrity impact is High.\nA:H - KASAN reports slab-use-after-free in ip6_tnl_start_xmit()/kfree_skb and the reproducer panics the kernel. Any skb double-free can oops or panic even if not fully exploited, so availability impact is High."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/ipv6/ip6_tunnel.c"], "versions": [{"version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "6e8eff8ed13b14708bc39f170144eacde494aac6", "status": "affected", "versionType": "git"}, {"version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "dc1a319a4815c074914e2812e0e9cd0164ca682b", "status": "affected", "versionType": "git"}, {"version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "629d5557e635cdbc109a14ed913ba5a540e3f79a", "status": "affected", "versionType": "git"}, {"version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "defa0adeff132cc90ed66915b9a104d9393e1e54", "status": "affected", "versionType": "git"}, {"version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "37df5bc6b5ccad88c2faa0f5466f150178882b74", "status": "affected", "versionType": "git"}, {"version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "b36dfd6e8cff00cea81c11cc0af88d1564763461", "status": "affected", "versionType": "git"}, {"version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52", "status": "affected", "versionType": "git"}, {"version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "87f21b59ddc618eff9670c174842964ad65fdade", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/ipv6/ip6_tunnel.c"], "versions": [{"version": "4.7", "status": "affected"}, {"version": "0", "lessThan": "4.7", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.270", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.221", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.188", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.157", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.7", "versionEndExcluding": "5.10.270"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.7", "versionEndExcluding": "5.15.221"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.7", "versionEndExcluding": "6.1.188"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.7", "versionEndExcluding": "6.6.157"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.7", "versionEndExcluding": "6.12.109"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.7", "versionEndExcluding": "6.18.50"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.7", "versionEndExcluding": "7.2.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.7", "versionEndExcluding": "7.3"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/6e8eff8ed13b14708bc39f170144eacde494aac6"}, {"url": "https://git.kernel.org/stable/c/dc1a319a4815c074914e2812e0e9cd0164ca682b"}, {"url": "https://git.kernel.org/stable/c/629d5557e635cdbc109a14ed913ba5a540e3f79a"}, {"url": "https://git.kernel.org/stable/c/defa0adeff132cc90ed66915b9a104d9393e1e54"}, {"url": "https://git.kernel.org/stable/c/37df5bc6b5ccad88c2faa0f5466f150178882b74"}, {"url": "https://git.kernel.org/stable/c/b36dfd6e8cff00cea81c11cc0af88d1564763461"}, {"url": "https://git.kernel.org/stable/c/8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52"}, {"url": "https://git.kernel.org/stable/c/87f21b59ddc618eff9670c174842964ad65fdade"}], "title": "ip6_tunnel: use skb_cow_head() in ip6_tnl_xmit()", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-89563", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-16T19:24:12.096672Z"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:26:44.202Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-89563", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "total"}], "version": "2.0.3", "timestamp": "2026-10-16T19:24:12.096672Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:24:12.677Z"}}], "cna": {"title": "ip6_tunnel: use skb_cow_head() in ip6_tnl_xmit()", "metrics": [{"cvssV3_1": {"version": "3.1", "baseScore": 7.8, "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}, "scenarios": [{"lang": "en", "value": "AV:L - The double-free is in ip6_tnl_xmit() on the ip6tnl/ip6gre transmit path. The reliable trigger is local: create a collect-metadata tunnel with FOU/GUE encap via rtnetlink, then push a packet through ip6_tnl_start_xmit() with tc tunnel_key+mirred. Ordinary remote packets on a working ip6tnl do not hit the post-realloc error path.\nAC:L - Once the collect-md device is created with non-NONE encap, any skb that needs headroom expansion takes skb_realloc_headroom(), consume_skb()s the original, then deterministically fails the collect_md/encap check so the caller kfree_skb()s the stale pointer. The published PoC reproduces this without a race or lucky layout.\nPR:L - Creating ip6tnl/ip6gre and tc filters needs CAP_NET_ADMIN, which an unprivileged user gets in their own user and network namespaces (unshare -Urn). The reporter confirmed this userns path; the resulting skb double-free is not confined to that namespace.\nUI:N - The attacker creates the tunnel, installs the tc redirect, and generates the packet themselves. No other user must mount a filesystem, open a file, or otherwise interact.\nS:U - The skb double-free corrupts kernel heap (skbuff_head_cache) on the same host. This is standard in-kernel memory corruption, not a VM escape, IOMMU/DMA bypass, or other cross-authority impact.\nC:H - consume_skb() frees the original skb and the caller later kfree_skb()s that stale pointer, a slab use-after-free/double-free. Reclaiming the skbuff_head_cache object yields an arbitrary kernel read primitive, so confidentiality impact is High.\nI:H - The same skb double-free/UAF is a heap primitive: the freed sk_buff can be sprayed and the second free or a later dereference used for an arbitrary write or control-flow hijack, so integrity impact is High.\nA:H - KASAN reports slab-use-after-free in ip6_tnl_start_xmit()/kfree_skb and the reproducer panics the kernel. Any skb double-free can oops or panic even if not fully exploited, so availability impact is High."}]}], "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "6e8eff8ed13b14708bc39f170144eacde494aac6", "versionType": "git"}, {"status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "dc1a319a4815c074914e2812e0e9cd0164ca682b", "versionType": "git"}, {"status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "629d5557e635cdbc109a14ed913ba5a540e3f79a", "versionType": "git"}, {"status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "defa0adeff132cc90ed66915b9a104d9393e1e54", "versionType": "git"}, {"status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "37df5bc6b5ccad88c2faa0f5466f150178882b74", "versionType": "git"}, {"status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "b36dfd6e8cff00cea81c11cc0af88d1564763461", "versionType": "git"}, {"status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52", "versionType": "git"}, {"status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "lessThan": "87f21b59ddc618eff9670c174842964ad65fdade", "versionType": "git"}], "programFiles": ["net/ipv6/ip6_tunnel.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "4.7"}, {"status": "unaffected", "version": "0", "lessThan": "4.7", "versionType": "semver"}, {"status": "unaffected", "version": "5.10.270", "versionType": "semver", "lessThanOrEqual": "5.10.*"}, {"status": "unaffected", "version": "5.15.221", "versionType": "semver", "lessThanOrEqual": "5.15.*"}, {"status": "unaffected", "version": "6.1.188", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.157", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.109", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.18.50", "versionType": "semver", "lessThanOrEqual": "6.18.*"}, {"status": "unaffected", "version": "7.2.4", "versionType": "semver", "lessThanOrEqual": "7.2.*"}, {"status": "unaffected", "version": "7.3", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["net/ipv6/ip6_tunnel.c"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/6e8eff8ed13b14708bc39f170144eacde494aac6"}, {"url": "https://git.kernel.org/stable/c/dc1a319a4815c074914e2812e0e9cd0164ca682b"}, {"url": "https://git.kernel.org/stable/c/629d5557e635cdbc109a14ed913ba5a540e3f79a"}, {"url": "https://git.kernel.org/stable/c/defa0adeff132cc90ed66915b9a104d9393e1e54"}, {"url": "https://git.kernel.org/stable/c/37df5bc6b5ccad88c2faa0f5466f150178882b74"}, {"url": "https://git.kernel.org/stable/c/b36dfd6e8cff00cea81c11cc0af88d1564763461"}, {"url": "https://git.kernel.org/stable/c/8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52"}, {"url": "https://git.kernel.org/stable/c/87f21b59ddc618eff9670c174842964ad65fdade"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nip6_tunnel: use skb_cow_head() in ip6_tnl_xmit()\n\nip6_tnl_xmit() may need to expand headroom before it can push the\nouter IPv6 and optional encap headers. It currently does that with\nskb_realloc_headroom(), copies skb->sk ownership, consumes the original\nskb, and then continues processing with the replacement skb kept only in\nits local variable.\n\nThat is safe only if the helper cannot fail afterwards. But this helper\nstill has post-reallocation error exits. collect_md tunnels reject\nnon-NONE encap after the replacement, and ip6_tnl_encap() can also fail\nlater. In those cases the helper returns an error to its callers while\nthe caller still only has the original skb pointer.\n\nBoth ip6_tnl_start_xmit() and the IPv6 GRE paths free the caller skb on\nerror, so they can end up freeing an skb that ip6_tnl_xmit() already\nconsumed.\n\nUse skb_cow_head() instead. It provides the required headroom and\nwritability without privately replacing the caller-owned skb, so later\nerror returns cannot leave callers with a stale pointer.\n\nThe Ethernet users, ip6gretap and ip6erspan, clear IFF_TX_SKB_SHARING\nand already call skb_cow_head() before entering ip6_tnl_xmit(). They do\nnot rely on the removed skb_shared() reallocation. This also makes the\nIPv6 tunnel path consistent with ip_tunnel_xmit()."}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.10.270", "versionStartIncluding": "4.7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.15.221", "versionStartIncluding": "4.7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.1.188", "versionStartIncluding": "4.7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.6.157", "versionStartIncluding": "4.7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.12.109", "versionStartIncluding": "4.7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "6.18.50", "versionStartIncluding": "4.7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.2.4", "versionStartIncluding": "4.7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "7.3", "versionStartIncluding": "4.7"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:48:56.784Z"}}}, "cveMetadata": {"cveId": "CVE-2026-89563", "state": "PUBLISHED", "dateUpdated": "2026-10-19T08:48:56.784Z", "dateReserved": "2026-09-11T19:38:34.725Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2026-09-11T19:44:34.375Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/ipv6/ip6_tunnel.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "6e8eff8ed13b14708bc39f170144eacde494aac6", "status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "versionType": "git"}, {"lessThan": "dc1a319a4815c074914e2812e0e9cd0164ca682b", "status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "versionType": "git"}, {"lessThan": "629d5557e635cdbc109a14ed913ba5a540e3f79a", "status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "versionType": "git"}, {"lessThan": "defa0adeff132cc90ed66915b9a104d9393e1e54", "status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "versionType": "git"}, {"lessThan": "37df5bc6b5ccad88c2faa0f5466f150178882b74", "status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "versionType": "git"}, {"lessThan": "b36dfd6e8cff00cea81c11cc0af88d1564763461", "status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "versionType": "git"}, {"lessThan": "8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52", "status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "versionType": "git"}, {"lessThan": "87f21b59ddc618eff9670c174842964ad65fdade", "status": "affected", "version": "058214a4d1dfefed9f01a277fadd3590acb5f990", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/ipv6/ip6_tunnel.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "4.7"}, {"lessThan": "4.7", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.10.*", "status": "unaffected", "version": "5.10.270", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.221", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.188", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.157", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.109", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.50", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.4", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nip6_tunnel: use skb_cow_head() in ip6_tnl_xmit()\n\nip6_tnl_xmit() may need to expand headroom before it can push the\nouter IPv6 and optional encap headers. It currently does that with\nskb_realloc_headroom(), copies skb->sk ownership, consumes the original\nskb, and then continues processing with the replacement skb kept only in\nits local variable.\n\nThat is safe only if the helper cannot fail afterwards. But this helper\nstill has post-reallocation error exits. collect_md tunnels reject\nnon-NONE encap after the replacement, and ip6_tnl_encap() can also fail\nlater. In those cases the helper returns an error to its callers while\nthe caller still only has the original skb pointer.\n\nBoth ip6_tnl_start_xmit() and the IPv6 GRE paths free the caller skb on\nerror, so they can end up freeing an skb that ip6_tnl_xmit() already\nconsumed.\n\nUse skb_cow_head() instead. It provides the required headroom and\nwritability without privately replacing the caller-owned skb, so later\nerror returns cannot leave callers with a stale pointer.\n\nThe Ethernet users, ip6gretap and ip6erspan, clear IFF_TX_SKB_SHARING\nand already call skb_cow_head() before entering ip6_tnl_xmit(). They do\nnot rely on the removed skb_shared() reallocation. This also makes the\nIPv6 tunnel path consistent with ip_tunnel_xmit()."}], "id": "CVE-2026-89563", "lastModified": "2026-10-19T09:17:52.040", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-89563", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-10-16T19:24:12.096672Z", "version": "2.0.3"}}]}, "published": "2026-09-11T20:19:40.193", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/37df5bc6b5ccad88c2faa0f5466f150178882b74"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/629d5557e635cdbc109a14ed913ba5a540e3f79a"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6e8eff8ed13b14708bc39f170144eacde494aac6"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/87f21b59ddc618eff9670c174842964ad65fdade"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/b36dfd6e8cff00cea81c11cc0af88d1564763461"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/dc1a319a4815c074914e2812e0e9cd0164ca682b"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/defa0adeff132cc90ed66915b9a104d9393e1e54"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: Linux Kernel: Memory corruption in ip6_tunnel due to double-free vulnerability", "id": "2532305", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2532305"}, "csaw": false, "cvss3": {"cvss3_base_score": "4.4", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-1341", "details": ["A flaw was found in the `ip6_tunnel` module of the Linux kernel. Incorrect handling of socket buffers (skb) during headroom reallocation in the `ip6_tnl_xmit()` function can lead to a double-free vulnerability. This occurs when an error path is taken after the original skb has been consumed, but the caller still holds a pointer to it, potentially allowing the same memory to be freed twice. This memory corruption issue could lead to a denial of service or potentially arbitrary code execution."], "name": "CVE-2026-89563", "public_date": "2026-09-11T19:44:34Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-89563\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-89563\nhttps://git.kernel.org/stable/c/37df5bc6b5ccad88c2faa0f5466f150178882b74\nhttps://git.kernel.org/stable/c/87f21b59ddc618eff9670c174842964ad65fdade\nhttps://git.kernel.org/stable/c/8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52\nhttps://git.kernel.org/stable/c/b36dfd6e8cff00cea81c11cc0af88d1564763461"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[058214a4d1dfefed9f01a277fadd3590acb5f990,37df5bc6b5ccad88c2faa0f5466f150178882b74)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[058214a4d1dfefed9f01a277fadd3590acb5f990,b36dfd6e8cff00cea81c11cc0af88d1564763461)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[058214a4d1dfefed9f01a277fadd3590acb5f990,8fc56ca49fc0ee1725b55c67bb43ab0dd01f3f52)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[058214a4d1dfefed9f01a277fadd3590acb5f990,87f21b59ddc618eff9670c174842964ad65fdade)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "4.7"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0,4.7)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.12.109,6.13.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.50,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.2.4,7.3.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.3-rc1,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-09-12T04:30:07.741053+00:00", "updated": "2026-09-15T22:00:17.604465+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}