{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64581","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-07-19T15:36:31.798Z","datePublished":"2026-08-05T08:09:35.556Z","dateUpdated":"2026-08-17T04:58:01.772Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-17T04:58:01.772Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nxfrm: fix sk_dst_cache double-free in xfrm_user_policy()\n\nxfrm_user_policy() clears the socket dst cache with __sk_dst_reset(),\ni.e. the non-atomic __sk_dst_set(sk, NULL): it reads sk_dst_cache with\nrcu_dereference_protected(), stores NULL and dst_release()s the old dst.\nThat is only safe if no other thread modifies sk_dst_cache concurrently.\n\nFor a connected UDP socket that does not hold: the transmit fast path\n(udp_sendmsg -> sk_dst_check -> sk_dst_reset) resets the cache locklessly\nwith an atomic xchg(). A per-socket policy change racing a send can make\nboth sides observe the same old dst and each dst_release() it, dropping\nthe socket's single reference twice and freeing the xfrm_dst bundle while\nit is still referenced:\n\n  BUG: KASAN: slab-use-after-free in dst_release\n  Write of size 4 at addr ffff88801897b6c0 by task exploit/155\n  Call Trace:\n   ...\n   dst_release (... ./include/linux/rcuref.h:109)\n   xfrm_user_policy (./include/net/sock.h:2239 ./include/net/sock.h:2256 net/xfrm/xfrm_state.c:3053)\n   do_ip_setsockopt (net/ipv4/ip_sockglue.c:1347)\n   ip_setsockopt (net/ipv4/ip_sockglue.c:1417)\n   do_sock_setsockopt (net/socket.c:2368)\n   __sys_setsockopt (net/socket.c:2393)\n   __x64_sys_setsockopt (net/socket.c:2396)\n   do_syscall_64 (arch/x86/entry/syscall_64.c:94)\n   entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121)\n\nReachable by an unprivileged user via a user+network namespace.\n\nUse the atomic sk_dst_reset() so the cache is cleared and released with a\nsingle xchg(): whichever side wins releases the dst once, the other sees\nNULL and does nothing. Behaviour is otherwise unchanged."}],"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 - Triggered via setsockopt(IP_XFRM_POLICY/IP_IPSEC_POLICY) on a local socket racing concurrent udp_sendmsg; entry is a local syscall path (do_ip_setsockopt -> xfrm_user_policy), not packet processing.\nAC:L - Attacker controls both sides of the race (one thread setsockopt to clear/apply per-socket xfrm policy, another sendmsg on the same connected UDP socket) and can create the obsolete xfrm_dst precondition in their netns, retrying until the double dst_release wins.\nPR:L - Path requires CAP_NET_ADMIN checked with sockopt_ns_capable(sock_net(sk)->user_ns), which an unprivileged user obtains via user+network namespaces; the fix commit explicitly states this reachability.\nUI:N - Exploitation uses only the attacker's own socket, threads, and setsockopt/sendmsg loops; no victim action or cooperation is required.\nS:U - Double-free/UAF of the socket's dst_entry/xfrm_dst is standard local kernel memory corruption within the host kernel authority, not a VM escape or other cross-boundary impact.\nC:H - Double dst_release frees the xfrm_dst slab object while still referenced, yielding a use-after-free that can be reclaimed/sprayed to disclose kernel memory via corrupted dst contents and ops.\nI:H - The UAF targets a dst_entry with function pointers (ops/input/output) used on transmit, enabling heap reuse for arbitrary write and control-flow hijack consistent with comparable sk_dst_cache races.\nA:H - The KASAN slab-use-after-free in dst_release demonstrates kernel memory corruption that can oops/panic, and the attacker can repeat the race freely."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_state.c"],"versions":[{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","lessThan":"96b678d08268b5f5c6fc99d4289d9b7e334fc683","status":"affected","versionType":"git"},{"version":"2b06cdf3e688b98fcc9945873b5d42792bd4eee0","lessThan":"c283e9ada7fcb7dd4b10592623086b2e6d2f9925","status":"affected","versionType":"git"},{"version":"72f157be2f81910ae759bfe2e5c2256fc4625645","status":"affected","versionType":"git"},{"version":"9e9fe58a92a46c6d154d2901735bf230d91b8507","status":"affected","versionType":"git"},{"version":"adc1ec6cdc20d430aa01b86497220709b9149466","status":"affected","versionType":"git"},{"version":"b54033eb1cfd77aba471269ddd804ed8d3e35dea","status":"affected","versionType":"git"},{"version":"c9e82cb34c3c2ee895af01bc899c6ed0bc6eb04a","status":"affected","versionType":"git"},{"version":"5eef9b51114fcc65651d671add52f267f91b9451","status":"affected","versionType":"git"},{"version":"3.16.52","lessThan":"3.17","status":"affected","versionType":"semver"},{"version":"4.4.163","lessThan":"4.5","status":"affected","versionType":"semver"},{"version":"3.18.101","lessThan":"3.19","status":"affected","versionType":"semver"},{"version":"4.1.52","lessThan":"4.2","status":"affected","versionType":"semver"},{"version":"4.4.123","lessThan":"4.5","status":"affected","versionType":"semver"},{"version":"4.9.89","lessThan":"4.10","status":"affected","versionType":"semver"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xfrm/xfrm_state.c"],"versions":[{"version":"4.14","status":"affected"},{"version":"0","lessThan":"4.14","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":"4.14","versionEndExcluding":"7.1.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.14","versionEndExcluding":"7.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.16.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4.163"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.18.101"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1.52"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.4.123"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.9.89"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/96b678d08268b5f5c6fc99d4289d9b7e334fc683"},{"url":"https://git.kernel.org/stable/c/c283e9ada7fcb7dd4b10592623086b2e6d2f9925"}],"title":"xfrm: fix sk_dst_cache double-free in xfrm_user_policy()","x_generator":{"engine":"bippy-1.2.0"}}}}