CVE-2026-52927

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: ebtables: fix OOB read in compat_mtw_from_user Luxiao Xu says: The function compat_mtw_from_user() converts ebtables extensions from 32-bit user structures to kernel native structures. However, it lacks proper validation of the user-supplied match_size/target_size. When certain extensions are processed, the kernel-side translation logic may perform memory accesses based on the extension's expected size. If the user provides a size smaller than what the extension requires, it results in an out-of-bounds read as reported by KASAN. This fix introduces a check to ensure match_size is at least as large as the extension's required compatsize. This covers matches, watchers, and targets, while maintaining compatibility with standard targets. AFAIU this is relevant for matches that need to go though match->compat_from_user() call. Those that use plain memcpy with the user-provided size are ok because the caller checks that size vs the start of the next rule entry offset (which itself is checked vs. total size copied from userspace). The ->compat_from_user() callbacks assume they can read compatsize bytes, so they need this extra check. Based on an earlier patch from Luxiao Xu.

PUBLISHED Reserved 2026-06-09 | Published 2026-06-24 | Updated 2026-06-24 | Assigner Linux

Product status

References

git.kernel.org/...c/d7a8fb6f10d55a1c37b0bf8c20cca24dffd76e00

git.kernel.org/...c/21af4c030567d2e6c89bb927bc18b51fba52a400

git.kernel.org/...c/dad9ebf8107955bb54bd3f9cf22591b6ff37bac1

git.kernel.org/...c/a27cb7325a6c69970041c7f8541fafed5a1ea3ec

git.kernel.org/...c/7ad0e463fc7eafae2141cc38054264636f8b3e94

git.kernel.org/...c/bf8e8eac7ede51dc318e06acef5a896dcbba7595

git.kernel.org/...c/fcc4c043d137e7f1de4673dba1f3116e45377c67

git.kernel.org/...c/f438d1786d657d57790c5d138d6db3fc9fdac392

cve.org (CVE-2026-52927)

nvd.nist.gov (CVE-2026-52927)

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