CVE-2026-53250xsk: cache csum_start/csum_offset to fix TOCTOU in xsk_skb_metadata()
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 48eb03dd26304c24f03bdbb9382e89c8564e71df before eb778aed8a9b2381668fcb1247ae4fa011224768; 48eb03dd26304c24f03bdbb9382e89c8564e71df builds before 0dfe05b938435892875e07771170051346412df9; from 48eb03dd26304c24f03bdbb9382e89c8564e71df before bfdfd2706d5fb2cd496a1506e680daf979309c8b; 48eb03dd26304c24f03bdbb9382e89c8564e71df builds before 22ba97ea9cc1f63a0d0244fae38057ed452b6ac7 | CNA record |
linux linux_kernel linux:linux_kernel | from 6.8 before 6.18.36; from 6.19 before 7.0.13; 7.1; 7.1; 7.1; 7.1; 7.1; 7.1 | NVD |
References
- https://git.kernel.org/stable/c/eb778aed8a9b2381668fcb1247ae4fa011224768
- https://git.kernel.org/stable/c/0dfe05b938435892875e07771170051346412df9patch
- https://git.kernel.org/stable/c/bfdfd2706d5fb2cd496a1506e680daf979309c8bpatch
- https://git.kernel.org/stable/c/22ba97ea9cc1f63a0d0244fae38057ed452b6ac7patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.