Kernel memory disclosure via repeated macro evaluation
Published Apr 1, 2026 · Updated Apr 1, 2026
Out-of-bounds read in the AppArmor DFA matcher in Linux Kernel allows local users to read kernel memory through crafted file paths. The match_char() macro evaluates *str++ repeatedly while traversing differential-encoding chains, advancing the input pointer beyond its buffer and making aa_dfa_match read adjacent slab data. Exploitation requires local low-privileged access and an active AppArmor policy using differential encoding; the memory exposure can support privilege escalation or container escape.
Summary
What happened
Out-of-bounds read in the AppArmor DFA matcher in Linux Kernel allows local users to read kernel memory through crafted file paths. The match_char() macro evaluates *str++ repeatedly while traversing differential-encoding chains, advancing the input pointer beyond its buffer and making aa_dfa_match read adjacent slab data. Exploitation requires local low-privileged access and an active AppArmor policy using differential encoding; the memory exposure can support privilege escalation or container escape.
The record
- CVE
- CVE-2026-23406
- Published
- Apr 1, 2026
- Updated
- Apr 1, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- CWE-125, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Apr 1, 2026CVE publishedPublication date reported by the CVE source.
- Apr 1, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=074c1cd798cb0b481d7eaa749b64aa416563c053 <0510d1ba0976f97f521feb2b75b0572ea5df3ceb
- Affected versionversion=074c1cd798cb0b481d7eaa749b64aa416563c053 <383b7270faf42564f133134c2fc3c24bbae52615
- Affected versionversion=074c1cd798cb0b481d7eaa749b64aa416563c053 <5a184f7cbdeaad17e16dedf3c17d0cd622edfed8
- Affected versionversion=074c1cd798cb0b481d7eaa749b64aa416563c053 <8756b68edae37ff546c02091989a4ceab3f20abd
- Affected versionversion=074c1cd798cb0b481d7eaa749b64aa416563c053 <b73c1dff8a9d7eeaebabf8097a5b2de192f40913
- Affected versionversion=4.17
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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