CVE-2026-31411

Description

In the Linux kernel, the following vulnerability has been resolved: net: atm: fix crash due to unvalidated vcc pointer in sigd_send() Reproducer available at [1]. The ATM send path (sendmsg -> vcc_sendmsg -> sigd_send) reads the vcc pointer from msg->vcc and uses it directly without any validation. This pointer comes from userspace via sendmsg() and can be arbitrarily forged: int fd = socket(AF_ATMSVC, SOCK_DGRAM, 0); ioctl(fd, ATMSIGD_CTRL); // become ATM signaling daemon struct msghdr msg = { .msg_iov = &iov, ... }; *(unsigned long *)(buf + 4) = 0xdeadbeef; // fake vcc pointer sendmsg(fd, &msg, 0); // kernel dereferences 0xdeadbeef In normal operation, the kernel sends the vcc pointer to the signaling daemon via sigd_enq() when processing operations like connect(), bind(), or listen(). The daemon is expected to return the same pointer when responding. However, a malicious daemon can send arbitrary pointer values. Fix this by introducing find_get_vcc() which validates the pointer by searching through vcc_hash (similar to how sigd_close() iterates over all VCCs), and acquires a reference via sock_hold() if found. Since struct atm_vcc embeds struct sock as its first member, they share the same lifetime. Therefore using sock_hold/sock_put is sufficient to keep the vcc alive while it is being used. Note that there may be a race with sigd_close() which could mark the vcc with various flags (e.g., ATM_VF_RELEASED) after find_get_vcc() returns. However, sock_hold() guarantees the memory remains valid, so this race only affects the logical state, not memory safety. [1]: https://gist.github.com/mrpre/1ba5949c45529c511152e2f4c755b0f3

Gravité et risque d'exploitation

CVE-2026-31411 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.13 %, ce qui la place devant 2.4 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions <=6.1.*, <=6.12.*, <1c8bda3df028d5e54134077dcd09f46ca8cfceb5, 2.6.12, <e3f80666c2739296c3b69a127300455c43aa1067, 0, 7.0, 6.1.165, 6.12.75, <2.6.12, 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, <=5.10.*, <=6.6.*, <69d3f9ee5489e6e8b66defcfa226e91d82393297, <=6.19.*, <ae88a5d2f29b69819dc7b04086734439d074a643, <440c9a5fc477a8ee259d8bf669531250b8398651, <c96549d07dfdd51aadf0722cfb40711574424840, <=6.18.*, <3e1a8b00095246a9a2b46b57f6d471c6d3c00ed2, 6.6.128, 5.10.252, <21c303fec138c002f90ed33bce60e807d53072bb, 6.19.4, <=*, <=5.15.*, 5.15.202, 6.18.14) 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/c96549d07dfdd51aadf0722cfb40711574424840
• https://git.kernel.org/stable/c/1c8bda3df028d5e54134077dcd09f46ca8cfceb5
• https://git.kernel.org/stable/c/3e1a8b00095246a9a2b46b57f6d471c6d3c00ed2
• https://git.kernel.org/stable/c/e3f80666c2739296c3b69a127300455c43aa1067
• https://git.kernel.org/stable/c/21c303fec138c002f90ed33bce60e807d53072bb
• https://git.kernel.org/stable/c/69d3f9ee5489e6e8b66defcfa226e91d82393297
• https://git.kernel.org/stable/c/440c9a5fc477a8ee259d8bf669531250b8398651
• https://git.kernel.org/stable/c/ae88a5d2f29b69819dc7b04086734439d074a643