CVE-2026-74478

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-74478", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.903Z", "datePublished": "2026-08-15T12:27:12.549Z", "dateUpdated": "2026-08-19T16:37:30.555Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-19T16:37:30.555Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\num: vector: fix use-after-free in vector_mmsg_rx()\n\nWhen vector_mmsg_rx() discards a packet whose overlay header fails\nverify_header(), it frees the skb and continues the loop:\n\n\tif (header_check < 0) {\n\t\tdev_kfree_skb_irq(skb);\n\t\tvp->estats.rx_encaps_errors++;\n\t\tcontinue;\n\t}\n\nThe normal and short-packet paths fall through to the bottom of the\nloop body, which clears the consumed slot and advances the cursors:\n\n\t(*skbuff_vector) = NULL;\n\tmmsg_vector++;\n\tskbuff_vector++;\n\nThe verify_header() < 0 path skips that via continue, so the freed skb\nis left in skbuff_vector[] and the cursors do not advance. The next\niteration reads the same slot, gets the freed skb, and frees it again,\nproducing a refcount underflow / use-after-free in the RX path.\n\nDiscard the slot the same way the other paths do before continuing.\n\nOnly transports whose verify_header() can return negative are affected:\nGRE and L2TPv3 do so on a cookie/session-id mismatch (raw/tap do not),\nso any peer on such a transport can trigger it without authentication."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL"}, "scenarios": [{"lang": "en", "value": "AV:N - The bug is reached from remotely sent GRE or L2TPv3 packets processed by vector_mmsg_rx() via recvmmsg on the tunnel socket; the fix commit states any peer on those transports can trigger it without authentication.\nAC:L - An attacker reliably triggers verify_header() failure with a wrong GRE key or L2TPv3 session/cookie, and sending two or more malformed packets in one recvmmsg batch causes immediate double-free of the same skb without races or special memory layout.\nPR:N - No privileges on the UML instance are required; exploitation needs only the ability to send network packets on the configured GRE/L2TPv3 transport, and overlay keys/cookies are not authenticated security controls.\nUI:N - Exploitation is driven entirely by remote packets delivered to the vector netdev RX path and requires no victim user or administrator action beyond the interface already being up.\nS:U - The use-after-free corrupts sk_buff memory inside the UML kernel network driver and does not by itself cross a VM, IOMMU, or host-kernel security boundary.\nC:H - The refcount underflow/use-after-free leaves a dangling sk_buff pointer that can be reallocated and read through standard heap grooming, giving an arbitrary kernel memory disclosure primitive.\nI:H - Reclaiming the freed sk_buff enables attacker-controlled contents in kernel heap objects and can be leveraged for arbitrary write or control-flow hijack in the UML kernel context.\nA:H - The double-free in the RX path can immediately oops or panic the UML kernel, and an unauthenticated remote peer can retrigger the condition by sending additional malformed tunnel packets."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["arch/um/drivers/vector_kern.c"], "versions": [{"version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "967c779c9853d2a1cc9cd8e61d300250c348f3d9", "status": "affected", "versionType": "git"}, {"version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "a7bc015bb798c525e7a82dd14225c6aeb994274b", "status": "affected", "versionType": "git"}, {"version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "7dc9781e320d664c9bdd50003c9acfddf363d1e1", "status": "affected", "versionType": "git"}, {"version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "4b9601595e8b6b5d18878cac0aeabc687d241111", "status": "affected", "versionType": "git"}, {"version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "67d58ab4f2ccf7145f3da07e025735a09c79de1b", "status": "affected", "versionType": "git"}, {"version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "180ff4c81faf01ec4e06082c9daa7c40518ead89", "status": "affected", "versionType": "git"}, {"version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "804b681002ead233abf49a3efd681f5468a835f9", "status": "affected", "versionType": "git"}, {"version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "lessThan": "af421e9aed3920c7ac88c24daa48606c7112feca", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["arch/um/drivers/vector_kern.c"], "versions": [{"version": "4.17", "status": "affected"}, {"version": "0", "lessThan": "4.17", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.265", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.216", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.183", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.151", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.103", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.44", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.8", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "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": "4.17", "versionEndExcluding": "5.10.265"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "5.15.216"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "6.1.183"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "6.6.151"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "6.12.103"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "6.18.44"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "7.1.8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.17", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/967c779c9853d2a1cc9cd8e61d300250c348f3d9"}, {"url": "https://git.kernel.org/stable/c/a7bc015bb798c525e7a82dd14225c6aeb994274b"}, {"url": "https://git.kernel.org/stable/c/7dc9781e320d664c9bdd50003c9acfddf363d1e1"}, {"url": "https://git.kernel.org/stable/c/4b9601595e8b6b5d18878cac0aeabc687d241111"}, {"url": "https://git.kernel.org/stable/c/67d58ab4f2ccf7145f3da07e025735a09c79de1b"}, {"url": "https://git.kernel.org/stable/c/180ff4c81faf01ec4e06082c9daa7c40518ead89"}, {"url": "https://git.kernel.org/stable/c/804b681002ead233abf49a3efd681f5468a835f9"}, {"url": "https://git.kernel.org/stable/c/af421e9aed3920c7ac88c24daa48606c7112feca"}], "title": "um: vector: fix use-after-free in vector_mmsg_rx()", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["arch/um/drivers/vector_kern.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "967c779c9853d2a1cc9cd8e61d300250c348f3d9", "status": "affected", "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "versionType": "git"}, {"lessThan": "a7bc015bb798c525e7a82dd14225c6aeb994274b", "status": "affected", "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "versionType": "git"}, {"lessThan": "7dc9781e320d664c9bdd50003c9acfddf363d1e1", "status": "affected", "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "versionType": "git"}, {"lessThan": "4b9601595e8b6b5d18878cac0aeabc687d241111", "status": "affected", "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "versionType": "git"}, {"lessThan": "67d58ab4f2ccf7145f3da07e025735a09c79de1b", "status": "affected", "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "versionType": "git"}, {"lessThan": "180ff4c81faf01ec4e06082c9daa7c40518ead89", "status": "affected", "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "versionType": "git"}, {"lessThan": "804b681002ead233abf49a3efd681f5468a835f9", "status": "affected", "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "versionType": "git"}, {"lessThan": "af421e9aed3920c7ac88c24daa48606c7112feca", "status": "affected", "version": "49da7e64f33e80edffb1a9eeb230fa4c3f42dffb", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["arch/um/drivers/vector_kern.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "4.17"}, {"lessThan": "4.17", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.10.*", "status": "unaffected", "version": "5.10.265", "versionType": "semver"}, {"lessThanOrEqual": "5.15.*", "status": "unaffected", "version": "5.15.216", "versionType": "semver"}, {"lessThanOrEqual": "6.1.*", "status": "unaffected", "version": "6.1.183", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.151", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.103", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.44", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.8", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "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\num: vector: fix use-after-free in vector_mmsg_rx()\n\nWhen vector_mmsg_rx() discards a packet whose overlay header fails\nverify_header(), it frees the skb and continues the loop:\n\n\tif (header_check < 0) {\n\t\tdev_kfree_skb_irq(skb);\n\t\tvp->estats.rx_encaps_errors++;\n\t\tcontinue;\n\t}\n\nThe normal and short-packet paths fall through to the bottom of the\nloop body, which clears the consumed slot and advances the cursors:\n\n\t(*skbuff_vector) = NULL;\n\tmmsg_vector++;\n\tskbuff_vector++;\n\nThe verify_header() < 0 path skips that via continue, so the freed skb\nis left in skbuff_vector[] and the cursors do not advance. The next\niteration reads the same slot, gets the freed skb, and frees it again,\nproducing a refcount underflow / use-after-free in the RX path.\n\nDiscard the slot the same way the other paths do before continuing.\n\nOnly transports whose verify_header() can return negative are affected:\nGRE and L2TPv3 do so on a cookie/session-id mismatch (raw/tap do not),\nso any peer on such a transport can trigger it without authentication."}], "id": "CVE-2026-74478", "lastModified": "2026-08-19T17:21:04.947", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.8, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.9, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-08-15T13:17:52.600", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/180ff4c81faf01ec4e06082c9daa7c40518ead89"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4b9601595e8b6b5d18878cac0aeabc687d241111"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/67d58ab4f2ccf7145f3da07e025735a09c79de1b"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/7dc9781e320d664c9bdd50003c9acfddf363d1e1"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/804b681002ead233abf49a3efd681f5468a835f9"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/967c779c9853d2a1cc9cd8e61d300250c348f3d9"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/a7bc015bb798c525e7a82dd14225c6aeb994274b"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/af421e9aed3920c7ac88c24daa48606c7112feca"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: um: vector: fix use-after-free in vector_mmsg_rx()", "id": "2517007", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2517007"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-763", "details": ["In the Linux kernel, the following vulnerability has been resolved:\num: vector: fix use-after-free in vector_mmsg_rx()\nWhen vector_mmsg_rx() discards a packet whose overlay header fails\nverify_header(), it frees the skb and continues the loop:\nif (header_check < 0) {\ndev_kfree_skb_irq(skb);\nvp->estats.rx_encaps_errors++;\ncontinue;\n}\nThe normal and short-packet paths fall through to the bottom of the\nloop body, which clears the consumed slot and advances the cursors:\n(*skbuff_vector) = NULL;\nmmsg_vector++;\nskbuff_vector++;\nThe verify_header() < 0 path skips that via continue, so the freed skb\nis left in skbuff_vector[] and the cursors do not advance. The next\niteration reads the same slot, gets the freed skb, and frees it again,\nproducing a refcount underflow / use-after-free in the RX path.\nDiscard the slot the same way the other paths do before continuing.\nOnly transports whose verify_header() can return negative are affected:\nGRE and L2TPv3 do so on a cookie/session-id mismatch (raw/tap do not),\nso any peer on such a transport can trigger it without authentication.", "A flaw was found in the Linux kernel. A remote attacker, by sending specially crafted packets over GRE or L2TPv3 transports, could trigger a use-after-free vulnerability. This occurs in the `vector_mmsg_rx()` function when a packet's overlay header fails verification, causing the system to attempt to free an already freed network buffer. This issue leads to a denial of service."], "name": "CVE-2026-74478", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-08-15T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-74478\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-74478\nhttps://lore.kernel.org/linux-cve-announce/2026081536-CVE-2026-74478-7cf2@gregkh/T"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[49da7e64f33e80edffb1a9eeb230fa4c3f42dffb,4b9601595e8b6b5d18878cac0aeabc687d241111)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[49da7e64f33e80edffb1a9eeb230fa4c3f42dffb,67d58ab4f2ccf7145f3da07e025735a09c79de1b)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[49da7e64f33e80edffb1a9eeb230fa4c3f42dffb,180ff4c81faf01ec4e06082c9daa7c40518ead89)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[49da7e64f33e80edffb1a9eeb230fa4c3f42dffb,804b681002ead233abf49a3efd681f5468a835f9)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[49da7e64f33e80edffb1a9eeb230fa4c3f42dffb,af421e9aed3920c7ac88c24daa48606c7112feca)"}}], "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": "4.17"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,4.17)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.6.151,6.7.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.12.103,6.13.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[6.18.44,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.1.8,7.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2-rc6,*]"}}], "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": "2026-08-15T17:45:03.067778+00:00", "updated": "2026-08-21T21:30:17.763721+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}