CVE-2026-52927 — netfilter: ebtables: fix OOB read in compat_mtw_from_user
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.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.1% (30-day exploitation probability)+0
- Technical severity (high)+6
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Linux Linux, Linux Linux Kernel).
- Apply the fixed version or the patch documented under Remediation.
- Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Linux | Linux |
version 2.6.34≥ 81e675c227ec60a0bdcbb547dc530ebee23ff931 and < f438d1786d657d57790c5d138d6db3fc9fdac392≥ 81e675c227ec60a0bdcbb547dc530ebee23ff931 and < fcc4c043d137e7f1de4673dba1f3116e45377c67≥ 81e675c227ec60a0bdcbb547dc530ebee23ff931 and < bf8e8eac7ede51dc318e06acef5a896dcbba7595≥ 81e675c227ec60a0bdcbb547dc530ebee23ff931 and < 7ad0e463fc7eafae2141cc38054264636f8b3e94≥ 81e675c227ec60a0bdcbb547dc530ebee23ff931 and < a27cb7325a6c69970041c7f8541fafed5a1ea3ec≥ 81e675c227ec60a0bdcbb547dc530ebee23ff931 and < dad9ebf8107955bb54bd3f9cf22591b6ff37bac1≥ 81e675c227ec60a0bdcbb547dc530ebee23ff931 and < 21af4c030567d2e6c89bb927bc18b51fba52a400 and 1 more≥ 81e675c227ec60a0bdcbb547dc530ebee23ff931 and < d7a8fb6f10d55a1c37b0bf8c20cca24dffd76e00 |
Vulnerable | CVE Program (cve.org) e CISA ADP |
| Linux | Linux Kernel |
version 7.1-rc4version 7.1-rc5≥ 2.6.34 and < 5.10.259version 7.1-rc3version 7.1-rc2version 7.1-rc1≥ 6.19 and < 7.0.12≥ 6.13 and < 6.18.35 and 4 more≥ 6.7 and < 6.12.93≥ 6.2 and < 6.6.143≥ 5.16 and < 6.1.176≥ 5.11 and < 5.15.210 |
Vulnerable | NIST National Vulnerability Database |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 7.8 | CVSS 3.1 | High | 1.8 | 5.9 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database |
| 7.8 | CVSS 3.1 | High | — | — | Linux via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (score shown at the top: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.12%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
- Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · linux/linux
- Record published
- Fix documented
- CVSS changed · 7.8
- Source status changed · → Analyzed
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
8 on the record
- git.kernel.org/stable/c/fcc4c043d137e7f1de4673dba1f3116e45377c67
- git.kernel.org/stable/c/7ad0e463fc7eafae2141cc38054264636f8b3e94
- git.kernel.org/stable/c/21af4c030567d2e6c89bb927bc18b51fba52a400
- git.kernel.org/stable/c/d7a8fb6f10d55a1c37b0bf8c20cca24dffd76e00
- git.kernel.org/stable/c/f438d1786d657d57790c5d138d6db3fc9fdac392
- git.kernel.org/stable/c/dad9ebf8107955bb54bd3f9cf22591b6ff37bac1
- git.kernel.org/stable/c/a27cb7325a6c69970041c7f8541fafed5a1ea3ec
- git.kernel.org/stable/c/bf8e8eac7ede51dc318e06acef5a896dcbba7595
Elsewhere on this site
Related CVEs (same products)
- Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 14h
- Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 14h
- Unknown CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 1d
- Unknown CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 1d
- Unknown CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 1d
- Unknown CVE-2026-98427 net/sched: codel: bound the dropping loop per dequeue call 1d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No CISA SSVC assessment.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-52927 is "netfilter: ebtables: fix OOB read in compat_mtw_from_user", rated High. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.8 describes technical severity. EPSS 0.12% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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