CVE-2026-31411

MEDIUM EPSS 2.5%
Published Apr 8, 20262mo ago · Modified Jun 17, 20261w ago
5.5 CVSS 3.1
Medium
Find Similar
Published Apr 8, 2026 2mo ago
Last Modified Jun 17, 2026 1w ago

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 Details

Base Score
5.5
Exploitability
1.8
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
2.5% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-476 NULL Pointer Dereference Memory Safety

Affected Products 18

VendorProductVersionRange
linuxlinux_kernel*≥2.6.12.1  –  <5.10.252
linuxlinux_kernel*≥5.11  –  <5.15.202
linuxlinux_kernel*≥5.16  –  <6.1.165
linuxlinux_kernel*≥6.2  –  <6.6.128
linuxlinux_kernel*≥6.7  –  <6.12.75
linuxlinux_kernel*≥6.13  –  <6.18.14
linuxlinux_kernel*≥6.19  –  <6.19.4
linuxlinux_kernel2.6.12any
linuxlinux_kernel2.6.12any
linuxlinux_kernel2.6.12any
linuxlinux_kernel2.6.12any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any

References 8

  • git.kernel.org https://git.kernel.org/stable/c/1c8bda3df028d5e54134077dcd09f46ca8cfceb5
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/21c303fec138c002f90ed33bce60e807d53072bb
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/3e1a8b00095246a9a2b46b57f6d471c6d3c00ed2
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/440c9a5fc477a8ee259d8bf669531250b8398651
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/69d3f9ee5489e6e8b66defcfa226e91d82393297
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/ae88a5d2f29b69819dc7b04086734439d074a643
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c96549d07dfdd51aadf0722cfb40711574424840
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/e3f80666c2739296c3b69a127300455c43aa1067
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/1c8bda3df028d5e54134077dcd09f46ca8cfceb5
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/21c303fec138c002f90ed33bce60e807d53072bb
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/3e1a8b00095246a9a2b46b57f6d471c6d3c00ed2
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/440c9a5fc477a8ee259d8bf669531250b8398651
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/69d3f9ee5489e6e8b66defcfa226e91d82393297
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/ae88a5d2f29b69819dc7b04086734439d074a643
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/c96549d07dfdd51aadf0722cfb40711574424840
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/e3f80666c2739296c3b69a127300455c43aa1067
    Patch