| Name | CVE-2026-53250 |
| Description | 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. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| References | DLA-4817-1, DSA-6528-1 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| linux (PTS) | bookworm | 6.1.176-1 | fixed |
| bookworm (security) | 6.1.187-1 | fixed | |
| trixie | 6.12.107-1 | vulnerable | |
| trixie (security) | 6.12.111-1 | fixed | |
| forky | 7.2.8-1 | fixed | |
| sid | 7.2.9-1 | fixed | |
| linux-6.12 (PTS) | bookworm (security) | 6.12.111-1~deb12u1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| linux | source | bullseye | (not affected) | |||
| linux | source | bookworm | (not affected) | |||
| linux | source | trixie | 6.12.111-1 | DSA-6528-1 | ||
| linux | source | (unstable) | 7.0.13-1 | |||
| linux-6.12 | source | bookworm | 6.12.111-1~deb12u1 | DLA-4817-1 |
[bookworm] - linux <not-affected> (Vulnerable code not present)
[bullseye] - linux <not-affected> (Vulnerable code not present)
https://git.kernel.org/linus/22ba97ea9cc1f63a0d0244fae38057ed452b6ac7 (7.1-rc7)