Time-of-check Time-of-use (TOCTOU) Affecting perf6.18-debuginfo package, versions <1:6.18.36-69.134.amzn2023


Severity

Recommended
0.0
high
0
10

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.1% (2nd percentile)

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  • Snyk IDSNYK-AMZN2023-PERF618DEBUGINFO-18061880
  • published21 Jul 2026
  • disclosed25 Jun 2026

Introduced: 25 Jun 2026

CVE-2026-53250  (opens in a new tab)
CWE-367  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 perf6.18-debuginfo to version 1:6.18.36-69.134.amzn2023 or higher.
This issue was patched in ALAS2023-2026-1925.

NVD Description

Note: Versions mentioned in the description apply only to the upstream perf6.18-debuginfo package and not the perf6.18-debuginfo package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

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 Base Scores

version 3.1