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Findings

CVE-2026-31504

In the Linux kernel, the following vulnerability has been resolved: net: fix fanout UAF in packet_release() via NETDEV_UP race has a race window where can re-register…

Published Apr 22, 2026 · updated Oct 15, 2026 · linux linux kernel

In the Linux kernel, the following vulnerability has been resolved: net: fix fanout UAF in packet_release() via NETDEV_UP race has a race window where can re-register a socket into a fanout group's array. The re-registration is not cleaned up by , leaving a dangling pointer in the fanout array. does NOT zero in its section. After releasing , is still non-zero and still matches the bound device. A concurrent that already found the socket in can re-register the hook. For fanout sockets, this re-registration calls which adds the socket back into and increments , but does NOT increment . The fix sets to zero in while is held to prevent NETDEV_UP from linking, preventing the race window. This bug was found following an additional audit with Claude Code based on CVE-2025-38617.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 22, 2026 · NIST NVD

    Detected

    In the Linux kernel, the following vulnerability has been resolved: net: fix fanout UAF in packet_release() via NETDEV_UP race has a race window where can re-register a socket into a fanout group's array. The re-registration is not cleaned up by , leaving a dangling pointer in the fanout array. does NOT zero in its section. After releasing , is still non-zero and still matches the bound device. A

  2. Oct 15, 2026 · NIST NVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: net: fix fanout UAF in packet_release() via NETDEV_UP race has a race window where can re-register a socket into a fanout group's array. The re-registration is not cleaned up by , leaving a dangling pointer in the fanout array. does NOT zero in its section. After releasing , is still non-zero and still matches the bound device. A

Affected

  • cpe linux/linux kernelversion unspecified
  • cpe linux/linux kernel3.1

Sources

  • CVE.orgVulnerability recordCVE-2026-31504

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-31504

    30-day exploitation probability 0.1%

    first.org
  • NIST NVDVulnerability recordCVE-2026-31504

    In the Linux kernel, the following vulnerability has been resolved: net: fix fanout UAF in packet_release() via NETDEV_UP race has a race window where can re-register a socket into a fanout group's array. The re-registration is not cleaned

    nvd.nist.gov

References