CVE-2026-64581

Description

In the Linux kernel, the following vulnerability has been resolved: xfrm: fix sk_dst_cache double-free in xfrm_user_policy() xfrm_user_policy() clears the socket dst cache with __sk_dst_reset(), i.e. the non-atomic __sk_dst_set(sk, NULL): it reads sk_dst_cache with rcu_dereference_protected(), stores NULL and dst_release()s the old dst. That is only safe if no other thread modifies sk_dst_cache concurrently. For a connected UDP socket that does not hold: the transmit fast path (udp_sendmsg -> sk_dst_check -> sk_dst_reset) resets the cache locklessly with an atomic xchg(). A per-socket policy change racing a send can make both sides observe the same old dst and each dst_release() it, dropping the socket's single reference twice and freeing the xfrm_dst bundle while it is still referenced: BUG: KASAN: slab-use-after-free in dst_release Write of size 4 at addr ffff88801897b6c0 by task exploit/155 Call Trace: ... dst_release (... ./include/linux/rcuref.h:109) xfrm_user_policy (./include/net/sock.h:2239 ./include/net/sock.h:2256 net/xfrm/xfrm_state.c:3053) do_ip_setsockopt (net/ipv4/ip_sockglue.c:1347) ip_setsockopt (net/ipv4/ip_sockglue.c:1417) do_sock_setsockopt (net/socket.c:2368) __sys_setsockopt (net/socket.c:2393) __x64_sys_setsockopt (net/socket.c:2396) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) Reachable by an unprivileged user via a user+network namespace. Use the atomic sk_dst_reset() so the cache is cleared and released with a single xchg(): whichever side wins releases the dst once, the other sees NULL and does nothing. Behaviour is otherwise unchanged.

Gravité et risque d'exploitation

CVE-2026-64581 obtient un score CVSS de 7.8/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.12 %, ce qui la place devant 1.6 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions 6.1.185, <=6.1.*, <=6.12.*, <4.2, 6.12.106, 0, 5.10.267, <=7.1.*, <c283e9ada7fcb7dd4b10592623086b2e6d2f9925, 6.6.154, <4.10, <96b678d08268b5f5c6fc99d4289d9b7e334fc683, <=5.10.*, <=6.6.*, 4.4.163, 5eef9b51114fcc65651d671add52f267f91b9451, <f0ab9a71167bae308e05ab13b65e2007504a603f, 4.9.89, 3.18.101, 7.1.6, <4.5, <e8686fd8d18b99f3a9038683045b2f2338a7706d, 4.1.52, b54033eb1cfd77aba471269ddd804ed8d3e35dea, <=6.18.*, 6.18.47, 72f157be2f81910ae759bfe2e5c2256fc4625645, 4.4.123, <8dd8929b71c4f06c614f8f54c2cc070453faae16, 9e9fe58a92a46c6d154d2901735bf230d91b8507, <a9340ebdc13f8bb5063c0bc0b037ee7e640d4ae9, <=*, <0ea8f06454012d9e7f9c6e6253df710949bf6294, <4.14, <=5.15.*, <f833821e4b52ab6335d443ede5fb79c38e61d19a, 3.16.52, <3.17, c9e82cb34c3c2ee895af01bc899c6ed0bc6eb04a, <3.19, 2b06cdf3e688b98fcc9945873b5d42792bd4eee0, 7.2, 4.14, adc1ec6cdc20d430aa01b86497220709b9149466, 5.15.218) est présent sur votre parc.
• Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
• À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
• Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

• https://git.kernel.org/stable/c/e8686fd8d18b99f3a9038683045b2f2338a7706d
• https://git.kernel.org/stable/c/a9340ebdc13f8bb5063c0bc0b037ee7e640d4ae9
• https://git.kernel.org/stable/c/f833821e4b52ab6335d443ede5fb79c38e61d19a
• https://git.kernel.org/stable/c/f0ab9a71167bae308e05ab13b65e2007504a603f
• https://git.kernel.org/stable/c/8dd8929b71c4f06c614f8f54c2cc070453faae16
• https://git.kernel.org/stable/c/0ea8f06454012d9e7f9c6e6253df710949bf6294
• https://git.kernel.org/stable/c/96b678d08268b5f5c6fc99d4289d9b7e334fc683
• https://git.kernel.org/stable/c/c283e9ada7fcb7dd4b10592623086b2e6d2f9925