{"id":"CVE-2026-64581","title":"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","summary":"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, NUL…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","published":"2026-08-05","updated":"2026-08-08","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-64581","references":[{"url":"https://git.kernel.org/stable/c/96b678d08268b5f5c6fc99d4289d9b7e334fc683","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c283e9ada7fcb7dd4b10592623086b2e6d2f9925","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/e8686fd8d18b99f3a9038683045b2f2338a7706d"},{"url":"https://git.kernel.org/stable/c/a9340ebdc13f8bb5063c0bc0b037ee7e640d4ae9"},{"url":"https://git.kernel.org/stable/c/f833821e4b52ab6335d443ede5fb79c38e61d19a"},{"url":"https://git.kernel.org/stable/c/f0ab9a71167bae308e05ab13b65e2007504a603f"},{"url":"https://git.kernel.org/stable/c/8dd8929b71c4f06c614f8f54c2cc070453faae16"},{"url":"https://git.kernel.org/stable/c/0ea8f06454012d9e7f9c6e6253df710949bf6294"}],"tags":["nvd","cve.org"],"epss":0.00121,"epssPercentile":0.01924,"ingestedAt":"2026-08-08T21:30:13.001Z","vendor":"Linux","product":"Linux","affected":["Linux >= 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 < e8686fd8d18b99f3a9038683045b2f2338a7706d","Linux >= 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 < a9340ebdc13f8bb5063c0bc0b037ee7e640d4ae9","Linux >= 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 < f833821e4b52ab6335d443ede5fb79c38e61d19a","Linux >= 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 < f0ab9a71167bae308e05ab13b65e2007504a603f","Linux >= 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 < 8dd8929b71c4f06c614f8f54c2cc070453faae16","Linux >= 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 < 0ea8f06454012d9e7f9c6e6253df710949bf6294","Linux >= 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 < 96b678d08268b5f5c6fc99d4289d9b7e334fc683","Linux >= 2b06cdf3e688b98fcc9945873b5d42792bd4eee0 < c283e9ada7fcb7dd4b10592623086b2e6d2f9925","Linux 72f157be2f81910ae759bfe2e5c2256fc4625645","Linux 9e9fe58a92a46c6d154d2901735bf230d91b8507","Linux adc1ec6cdc20d430aa01b86497220709b9149466","Linux b54033eb1cfd77aba471269ddd804ed8d3e35dea","Linux c9e82cb34c3c2ee895af01bc899c6ed0bc6eb04a","Linux 5eef9b51114fcc65651d671add52f267f91b9451","Linux >= 3.16.52 < 3.17","Linux >= 4.4.163 < 4.5","Linux >= 3.18.101 < 3.19","Linux >= 4.1.52 < 4.2","Linux >= 4.4.123 < 4.5","Linux >= 4.9.89 < 4.10","Linux 4.14"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T15:43:16.753183Z"},"slug":"CVE-2026-64581","body":"## Overview\n\nIn 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}