CVE-2026-31411

Advisory lineage Upstream: 0 Downstream: 11
Analyzed
Published: 08 Apr 2026, 13:06
Last modified:14 Jul 2026, 12:47

Vulnerability Summary

Overall Risk (default)
low
22/100
CVSS Score
5.5 MEDIUM
v3.1 (nvd)
EPSS Score
0.13% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
None found
Dark Web
Not detected

Timeline

08 Apr 2026, 13:06
Published
Vulnerability first disclosed
14 Jul 2026, 12:47
Last Modified
Vulnerability information updated

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

CVSS Metrics

  • v3.1•MEDIUM•Score: 5.5CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Trends

Current EPSS score: 0.13%• Percentile: 3%

Techniques & Countermeasures

  • CWE-476•NULL Pointer Dereference

    The product dereferences a pointer that it expects to be valid but is NULL.

Affected Systems

  • linux•linux

    ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < c96549d07dfdd51aadf0722cfb40711574424840 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 1c8bda3df028d5e54134077dcd09f46ca8cfceb5 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 3e1a8b00095246a9a2b46b57f6d471c6d3c00ed2 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < e3f80666c2739296c3b69a127300455c43aa1067 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 21c303fec138c002f90ed33bce60e807d53072bb | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 69d3f9ee5489e6e8b66defcfa226e91d82393297 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 440c9a5fc477a8ee259d8bf669531250b8398651 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < ae88a5d2f29b69819dc7b04086734439d074a643 | 2.6.12

  • linux•linux kernel

    ≥ 2.6.12.1, < 5.10.252 | ≥ 5.11, < 5.15.202 | ≥ 5.16, < 6.1.165 | ≥ 6.2, < 6.6.128 | ≥ 6.7, < 6.12.75 | ≥ 6.13, < 6.18.14 | ≥ 6.19, < 6.19.4 | 2.6.12:rc2 | 2.6.12:rc3 | 2.6.12:rc4 | 2.6.12:rc5 | 7.0:rc1 | 7.0:rc2 | 7.0:rc3 | 7.0:rc4 | 7.0:rc5 | 7.0:rc6 | 7.0:rc7

References (10)