CVE-2026-53250

Status: UPDATED  |  Advisory ID: CVE-2026-53250

Key Details

Affected Products, Subsystems & Sectors

What to Know

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

xsk: cache csum_start/csum_offset to fix TOCTOU in xsk_skb_metadata()

The TX metadata area resides in the UMEM buffer which is memory-mapped

and concurrently writable by userspace. In xsk_skb_metadata(),

csum_start and csum_offset are read from shared memory for bounds

validation, then read again for skb assignment. A malicious userspace

application can race to overwrite these values between the two reads,

bypassing the bounds check and causing out-of-bounds memory access

during checksum computation in the transmit path.

Fix this by reading csum_start and csum_offset into local variables

once, then using the local copies for both validation and assignment.

Note that other metadata fields (flags, launch_time) and the cached

csum fields may be mutually inconsistent due to concurrent userspace

writes, but this is benign: the only security-critical invariant is

that each field's validated value is the same one used, which local

caching guarantees. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References