{"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"}}}}