VulnerabilityPublished 28 Oct 2026

CVE-2026-99110: Linux kernel · smb: client: fix heap overflow in cifs_do_set_acl()

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in d96f3365ce61c5f39602955af43c8174548dee98 : update Linux kernel when convenient.

Data as of 28 Oct 2026, 10:58 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

Patch: Available – fixed in d96f3365ce61c5f39602955af43c8174548dee98, 596b4062e6c75bdd85a7f2b7f2087a872dc420ac, 1dac61e2c29d1a71784604b48cf3b1234a65ec29

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to d96f3365ce61c5f39602955af43c8174548dee98, 596b4062e6c75bdd85a7f2b7f2087a872dc420ac or 1dac61e2c29d1a71784604b48cf3b1234a65ec29.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ dc1af4c4b4721abfa07b351063825acc7e69cc66, < d96f3365ce61c5f39602955af43c8174548dee98	Fixed in d96f3365ce61c5f39602955af43c8174548dee98
LinuxLinux	Affected ≥ dc1af4c4b4721abfa07b351063825acc7e69cc66, < 596b4062e6c75bdd85a7f2b7f2087a872dc420ac	Fixed in 596b4062e6c75bdd85a7f2b7f2087a872dc420ac
LinuxLinux	Affected ≥ dc1af4c4b4721abfa07b351063825acc7e69cc66, < 1dac61e2c29d1a71784604b48cf3b1234a65ec29	Fixed in 1dac61e2c29d1a71784604b48cf3b1234a65ec29
LinuxLinux	Affected =6.2	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix heap overflow in cifs_do_set_acl() cifs_set_acl() validates ACL size using posix_acl_xattr_size(): 4 + (count * 8) // 4-byte header + 8 bytes per ACE cifs_do_set_acl() then calls posix_acl_to_cifs() to write the CIFS wire format into the same buffer: 6 + (count * 10) // 6-byte header + 10 bytes per ACE An ACL that passes the xattr-based check in cifs_set_acl() can overflow the heap when posix_acl_to_cifs() writes the larger CIFS format. Validate the CIFS format size against the remaining buffer space and USHRT_MAX before converting--data_count is __u16, so sizes above USHRT_MAX truncate the on-wire packet length, causing the server to apply a partial ACL. Replace MaxDataCount = 1000 with min(CIFSMaxBufSize, USHRT_MAX).

References

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