CVE-2026-68170

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-68170", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-30T09:28:09.372Z", "datePublished": "2026-08-10T11:59:39.174Z", "dateUpdated": "2026-08-17T05:00:11.808Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:00:11.808Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: fix stale skb->sk reference on subflow close\n\nThe backlog list is updated by mptcp_data_ready() under\nmptcp_data_lock(). The cleanup of backlog references to a closing\nsubflow, however, was performed in mptcp_close_ssk(), before\n__mptcp_close_ssk() acquires the ssk lock, and while holding neither\nthe ssk lock nor mptcp_data_lock().\n\nBecause that traversal ran without mptcp_data_lock(), concurrent softirq\nRX processing on another CPU (subflow_data_ready() -> mptcp_data_ready()\n-> __mptcp_add_backlog(), under mptcp_data_lock()) could add a backlog\nentry referencing the ssk while the cleanup loop was in progress. Such\nan entry could be missed by the cleanup, or the concurrent list update\ncould corrupt the traversal, leaving skb->sk pointing at the ssk after\nit is freed.\n\nA later mptcp_backlog_purge() then dereferences the stale pointer,\ntriggering a warning in inet_sock_destruct() (ssk->sk_rmem_alloc != 0)\nfollowed by a use-after-free in mptcp_backlog_purge().\n\nFix this by moving the backlog cleanup into __mptcp_close_ssk(), after\nsubflow->closing is set to 1 and while the ssk lock is still held,\nserialized under mptcp_data_lock(). The cleanup runs only on the push\npath (MPTCP_CF_PUSH), where backlog references accumulate; on other\nteardown paths the caller already handles cleanup.\n\nWith subflow->closing set and mptcp_data_lock() held across the purge,\nany concurrent mptcp_data_ready() either completes its enqueue before\nthe purge runs and is caught, or observes closing=1 and bails out. Once\nmptcp_data_unlock() is reached, no new skb referencing the ssk can be\nenqueued, so the cleanup is exhaustive.\n\nRemove the unprotected traversal from mptcp_close_ssk() entirely."}], "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 in MPTCP receive/teardown on the TCP/IP stack; remote peers drive subflow_data_ready() RX softirq processing and can concurrently trigger subflow close via FIN/RST or data floods during mptcp_close_ssk(), reaching the race without local access.\nAC:L - The attacker controls both sides of the race by timing inbound packets against subflow teardown on an MPTCP connection they own; syzkaller reliably reproduced the UAF, and no uncontrollable memory layout or rare victim state is required beyond an active MPTCP session.\nPR:N - Exploitation needs only the ability to be an MPTCP/TCP peer on the network after handshake; no local account, CAP_NET_ADMIN, or application credentials on the victim are required to send data and close subflows remotely.\nUI:N - No victim user interaction is required beyond the system normally accepting or maintaining MPTCP connections; the attacker can trigger the race entirely through automated network traffic and connection management.\nS:U - The vulnerability corrupts kernel heap memory within the network stack security boundary on the affected host; it does not by itself cross VM, hypervisor, or IOMMU isolation boundaries.\nC:H - A missed backlog cleanup leaves skb->sk pointing at a freed subflow socket; later mptcp_backlog_purge() dereferences it in mptcp_borrow_fwdmem(), producing a slab use-after-free on struct sock that can disclose kernel memory.\nI:H - The UAF performs atomic_sub() writes to sk_rmem_alloc on a freed TCP socket object, corrupting attacker-influenced heap memory and providing a standard path to further arbitrary kernel write or control-flow hijack.\nA:H - Confirmed KASAN slab-use-after-free during mptcp_backlog_purge() causes inet_sock_destruct() warnings and kernel instability during socket teardown; UAF in softirq/close paths can panic or repeatedly crash the host."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/mptcp/protocol.c"], "versions": [{"version": "ee458a3f314e9c669ddd227bf5ab08354d9e75cc", "lessThan": "625fc6060864889fe3d370cdeffbbab762af3cb4", "status": "affected", "versionType": "git"}, {"version": "ee458a3f314e9c669ddd227bf5ab08354d9e75cc", "lessThan": "bd7aae448f6ee9d82599a4474664de1e6e91a535", "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/mptcp/protocol.c"], "versions": [{"version": "6.19", "status": "affected"}, {"version": "0", "lessThan": "6.19", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.6", "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": "6.19", "versionEndExcluding": "7.1.6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/625fc6060864889fe3d370cdeffbbab762af3cb4"}, {"url": "https://git.kernel.org/stable/c/bd7aae448f6ee9d82599a4474664de1e6e91a535"}], "title": "mptcp: fix stale skb->sk reference on subflow close", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/mptcp/protocol.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "625fc6060864889fe3d370cdeffbbab762af3cb4", "status": "affected", "version": "ee458a3f314e9c669ddd227bf5ab08354d9e75cc", "versionType": "git"}, {"lessThan": "bd7aae448f6ee9d82599a4474664de1e6e91a535", "status": "affected", "version": "ee458a3f314e9c669ddd227bf5ab08354d9e75cc", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/mptcp/protocol.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "6.19"}, {"lessThan": "6.19", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.6", "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\nmptcp: fix stale skb->sk reference on subflow close\n\nThe backlog list is updated by mptcp_data_ready() under\nmptcp_data_lock(). The cleanup of backlog references to a closing\nsubflow, however, was performed in mptcp_close_ssk(), before\n__mptcp_close_ssk() acquires the ssk lock, and while holding neither\nthe ssk lock nor mptcp_data_lock().\n\nBecause that traversal ran without mptcp_data_lock(), concurrent softirq\nRX processing on another CPU (subflow_data_ready() -> mptcp_data_ready()\n-> __mptcp_add_backlog(), under mptcp_data_lock()) could add a backlog\nentry referencing the ssk while the cleanup loop was in progress. Such\nan entry could be missed by the cleanup, or the concurrent list update\ncould corrupt the traversal, leaving skb->sk pointing at the ssk after\nit is freed.\n\nA later mptcp_backlog_purge() then dereferences the stale pointer,\ntriggering a warning in inet_sock_destruct() (ssk->sk_rmem_alloc != 0)\nfollowed by a use-after-free in mptcp_backlog_purge().\n\nFix this by moving the backlog cleanup into __mptcp_close_ssk(), after\nsubflow->closing is set to 1 and while the ssk lock is still held,\nserialized under mptcp_data_lock(). The cleanup runs only on the push\npath (MPTCP_CF_PUSH), where backlog references accumulate; on other\nteardown paths the caller already handles cleanup.\n\nWith subflow->closing set and mptcp_data_lock() held across the purge,\nany concurrent mptcp_data_ready() either completes its enqueue before\nthe purge runs and is caught, or observes closing=1 and bails out. Once\nmptcp_data_unlock() is reached, no new skb referencing the ssk can be\nenqueued, so the cleanup is exhaustive.\n\nRemove the unprotected traversal from mptcp_close_ssk() entirely."}], "id": "CVE-2026-68170", "lastModified": "2026-08-17T05:18:17.593", "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": "2026-08-10T13:20:03.637", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/625fc6060864889fe3d370cdeffbbab762af3cb4"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/bd7aae448f6ee9d82599a4474664de1e6e91a535"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: Linux kernel MPTCP: Use-after-free vulnerability", "id": "2513375", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2513375"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H", "status": "draft"}, "cwe": "CWE-825", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nmptcp: fix stale skb->sk reference on subflow close\nThe backlog list is updated by mptcp_data_ready() under\nmptcp_data_lock(). The cleanup of backlog references to a closing\nsubflow, however, was performed in mptcp_close_ssk(), before\n__mptcp_close_ssk() acquires the ssk lock, and while holding neither\nthe ssk lock nor mptcp_data_lock().\nBecause that traversal ran without mptcp_data_lock(), concurrent softirq\nRX processing on another CPU (subflow_data_ready() -> mptcp_data_ready()\n-> __mptcp_add_backlog(), under mptcp_data_lock()) could add a backlog\nentry referencing the ssk while the cleanup loop was in progress. Such\nan entry could be missed by the cleanup, or the concurrent list update\ncould corrupt the traversal, leaving skb->sk pointing at the ssk after\nit is freed.\nA later mptcp_backlog_purge() then dereferences the stale pointer,\ntriggering a warning in inet_sock_destruct() (ssk->sk_rmem_alloc != 0)\nfollowed by a use-after-free in mptcp_backlog_purge().\nFix this by moving the backlog cleanup into __mptcp_close_ssk(), after\nsubflow->closing is set to 1 and while the ssk lock is still held,\nserialized under mptcp_data_lock(). The cleanup runs only on the push\npath (MPTCP_CF_PUSH), where backlog references accumulate; on other\nteardown paths the caller already handles cleanup.\nWith subflow->closing set and mptcp_data_lock() held across the purge,\nany concurrent mptcp_data_ready() either completes its enqueue before\nthe purge runs and is caught, or observes closing=1 and bails out. Once\nmptcp_data_unlock() is reached, no new skb referencing the ssk can be\nenqueued, so the cleanup is exhaustive.\nRemove the unprotected traversal from mptcp_close_ssk() entirely.", "A flaw was found in the Linux kernel's Multipath TCP (MPTCP) feature. A timing issue, or race condition, can occur when a subflow is being closed, leading to a situation where the system attempts to use memory that has already been freed. This 'use-after-free' vulnerability arises because concurrent network data processing might interact improperly with the cleanup process. An attacker could potentially exploit this to cause a system crash (denial of service)."], "name": "CVE-2026-68170", "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"}, {"cpe": "cpe:/a:redhat:enterprise_linux_nvidia:", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux for NVIDIA 26"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Not affected", "package_name": "rhcos", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-08-10T11:59:39Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-68170\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-68170\nhttps://git.kernel.org/stable/c/625fc6060864889fe3d370cdeffbbab762af3cb4\nhttps://git.kernel.org/stable/c/bd7aae448f6ee9d82599a4474664de1e6e91a535"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[ee458a3f314e9c669ddd227bf5ab08354d9e75cc,625fc6060864889fe3d370cdeffbbab762af3cb4)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[ee458a3f314e9c669ddd227bf5ab08354d9e75cc,bd7aae448f6ee9d82599a4474664de1e6e91a535)"}}], "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": "generic", "value": "6.19"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0.0.0,6.19)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.1.6,7.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2-rc5,*]"}}], "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": "2026-08-10T16:30:04.950564+00:00", "updated": "2026-08-14T00:00:04.143263+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}