CVE-2026-52927
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk2th percentile - higher than 2% of all known CVEs
Summary
In the Linux kernel, a vulnerability was found in the ebtables module where the compat_mtw_from_user() function lacks proper validation of user-supplied match_size/target_size. This can cause an out-of-bounds read when converting ebtables extensions from 32-bit user structures to kernel native structures.
Risk Assessment
An attacker with privileges to configure ebtables could exploit this vulnerability to read kernel memory, potentially leading to sensitive data leakage or system instability.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit addressing the issue). If updating is not possible, restrict ebtables configuration access to trusted users only.
Original NVD description (English source)
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.