{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-72137", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-09T03:40:39.908Z", "datePublished": "2026-08-15T05:53:11.812Z", "dateUpdated": "2026-08-17T05:40:47.767Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:40:47.767Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: nat_keepalive: avoid double free on send error\n\nnat_keepalive_send() frees the keepalive skb whenever the IPv4 or IPv6\nsend helper reports an error.\n\nThat cleanup is only correct before the skb is handed to the output\npath. Once ip_build_and_send_pkt() or ip6_xmit() takes ownership, the\nnetworking stack may already have consumed the skb before returning an\nerror, so freeing it again is unsafe.\n\nHandle the pre-handoff failure cases inside nat_keepalive_send_ipv4()\nand nat_keepalive_send_ipv6(), where the caller still owns the skb, and\nkeep nat_keepalive_send() responsible only for family dispatch and the\nunsupported-family cleanup path." } ], "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 - On internet-facing IPsec VPN gateways using kernel NAT keepalive, a remote attacker can induce post-handoff outbound send failures (e.g., ENOMEM from network-driven memory pressure) when periodic keepalives are transmitted, reaching the vulnerable double-free path.\nAC:L - After an outbound ESP-in-UDP SA has NAT keepalive configured, an attacker can reliably force send errors where the stack already consumed the skb (ip6_xmit EMSGSIZE, ip_finish_output2 neighbour/ENOMEM paths) without uncontrollable races or memory layout dependencies.\nPR:N - Remote exploitation requires no privileges on the victim; it only needs a typical IPsec NAT-T deployment where userspace already set XFRMA_NAT_KEEPALIVE_INTERVAL. Local exploitation via user namespaces needs only CAP_NET_ADMIN (PR:L), not root in the init namespace.\nUI:N - No victim or administrator interaction is needed during exploitation; NAT keepalives are sent automatically by the kernel delayed work queue on the configured interval once the XFRM SA exists.\nS:U - Impact is kernel heap corruption and privilege escalation within the same security authority; this is not a VM escape, container breakout, or IOMMU/DMA boundary bypass.\nC:H - The skb double-free corrupts the slab allocator and yields use-after-free primitives that can be leveraged for arbitrary kernel memory disclosure, not merely a bounded leak or crash-only NULL dereference.\nI:H - Double-free heap corruption enables attacker-controlled reallocation of freed sk_buff objects, supporting arbitrary kernel memory writes, control-flow hijacking, and local privilege escalation.\nA:H - The double-free reliably causes slab corruption, kernel oops, or panic during keepalive send-error cleanup, providing immediate and repeatable denial of service on affected systems." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/xfrm/xfrm_nat_keepalive.c" ], "versions": [ { "version": "f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae", "lessThan": "d0a4dc7efa825bce60a8da8f7d43c864a159abde", "status": "affected", "versionType": "git" }, { "version": "f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae", "lessThan": "5b0c4c916f202b8fd13d12afb6af62b385622f81", "status": "affected", "versionType": "git" }, { "version": "f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae", "lessThan": "a8a7e6a9ff8a4c1f067694ddbd44be67fdf36693", "status": "affected", "versionType": "git" }, { "version": "f531d13bdfe3f4f084aaa8acae2cb0f02295f5ae", "lessThan": "226f4a490d1a938fc838d8f8c46a4eca864c0d78", "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/xfrm/xfrm_nat_keepalive.c" ], "versions": [ { "version": "6.11", "status": "affected" }, { "version": "0", "lessThan": "6.11", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.101", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "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": "6.11", "versionEndExcluding": "6.12.101" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.11", "versionEndExcluding": "6.18.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.11", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.11", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/d0a4dc7efa825bce60a8da8f7d43c864a159abde" }, { "url": "https://git.kernel.org/stable/c/5b0c4c916f202b8fd13d12afb6af62b385622f81" }, { "url": "https://git.kernel.org/stable/c/a8a7e6a9ff8a4c1f067694ddbd44be67fdf36693" }, { "url": "https://git.kernel.org/stable/c/226f4a490d1a938fc838d8f8c46a4eca864c0d78" } ], "title": "xfrm: nat_keepalive: avoid double free on send error", "x_generator": { "engine": "bippy-1.2.0" } } } }