Out-of-bounds Write Affecting linux-qemu-rc package, versions <7.1_rc3-r0


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.01% (4th percentile)

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  • Snyk IDSNYK-CHAINGUARDLATEST-LINUXQEMURC-16727809
  • published17 May 2026
  • disclosed1 May 2026

Introduced: 1 May 2026

CVE-2026-31696  (opens in a new tab)
CWE-787  (opens in a new tab)

How to fix?

Upgrade Chainguard linux-qemu-rc to version 7.1_rc3-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream linux-qemu-rc package and not the linux-qemu-rc package as distributed by Chainguard. See How to fix? for Chainguard relevant fixed versions and status.

In the Linux kernel, the following vulnerability has been resolved:

rxrpc: Fix missing validation of ticket length in non-XDR key preparsing

In rxrpc_preparse(), there are two paths for parsing key payloads: the XDR path (for large payloads) and the non-XDR path (for payloads <= 28 bytes). While the XDR path (rxrpc_preparse_xdr_rxkad()) correctly validates the ticket length against AFSTOKEN_RK_TIX_MAX, the non-XDR path fails to do so.

This allows an unprivileged user to provide a very large ticket length. When this key is later read via rxrpc_read(), the total token size (toksize) calculation results in a value that exceeds AFSTOKEN_LENGTH_MAX, triggering a WARN_ON().

[ 2001.302904] WARNING: CPU: 2 PID: 2108 at net/rxrpc/key.c:778 rxrpc_read+0x109/0x5c0 [rxrpc]

Fix this by adding a check in the non-XDR parsing path of rxrpc_preparse() to ensure the ticket length does not exceed AFSTOKEN_RK_TIX_MAX, bringing it into parity with the XDR parsing logic.

CVSS Base Scores

version 3.1