CVE-2026-31641

Technical Description

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

rxrpc: Fix RxGK token loading to check bounds

rxrpc_preparse_xdr_yfs_rxgk() reads the raw key length and ticket length

from the XDR token as u32 values and passes each through round_up(x, 4)

before using the rounded value for validation and allocation. When the raw

length is >= 0xfffffffd, round_up() wraps to 0, so the bounds check and

kzalloc both use 0 while the subsequent memcpy still copies the original

~4 GiB value, producing a heap buffer overflow reachable from an

unprivileged add_key() call.

Fix this by:

(1) Rejecting raw key lengths above AFSTOKEN_GK_KEY_MAX and raw ticket

lengths above AFSTOKEN_GK_TOKEN_MAX before rounding, consistent with

the caps that the RxKAD path already enforces via AFSTOKEN_RK_TIX_MAX.

(2) Sizing the flexible-array allocation from the validated raw key

length via struct_size_t() instead of the rounded value.

(3) Caching the raw lengths so that the later field a

Remediation

Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected Products

References