Heap corruption via undersized ACL conversion buffer
Published Oct 28, 2026 · Updated Oct 28, 2026
Heap overflow in the Linux 6.2 SMB client allows local users to overwrite kernel heap memory via a crafted POSIX ACL. cifs_set_acl() checks the smaller xattr representation, but cifs_do_set_acl() calls posix_acl_to_cifs() to write the larger wire representation into the same buffer without checking its required size. Reachability requires access to the legacy SMB1 POSIX ACL path through setxattr; the published evidence establishes heap corruption, not successful code execution or privilege escalation.
Summary
What happened
Heap overflow in the Linux 6.2 SMB client allows local users to overwrite kernel heap memory via a crafted POSIX ACL. cifs_set_acl() checks the smaller xattr representation, but cifs_do_set_acl() calls posix_acl_to_cifs() to write the larger wire representation into the same buffer without checking its required size. Reachability requires access to the legacy SMB1 POSIX ACL path through setxattr; the published evidence establishes heap corruption, not successful code execution or privilege escalation.
The record
- CVE
- CVE-2026-99110
- Published
- Oct 28, 2026
- Updated
- Oct 28, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Oct 28, 2026CVE publishedPublication date reported by the CVE source.
- Oct 28, 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=6.2
- Affected versionversion=dc1af4c4b4721abfa07b351063825acc7e69cc66 <1dac61e2c29d1a71784604b48cf3b1234a65ec29
- Affected versionversion=dc1af4c4b4721abfa07b351063825acc7e69cc66 <596b4062e6c75bdd85a7f2b7f2087a872dc420ac
- Affected versionversion=dc1af4c4b4721abfa07b351063825acc7e69cc66 <d96f3365ce61c5f39602955af43c8174548dee98
What conditions does exploitation require?
What is affected?
Published CVSS scores
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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.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
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Public exploit references
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Technologies
Your stack
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Your stack
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