CVE-2026-97559: Linux kernel · smb: client: fail DACL rewrite when the new DACL exceeds 64K
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 26 Oct 2026, 14:05 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Exploitation evidence
Disclosed: evidence found.
CVE published 25 Sep 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.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A fix is available that changes the internal size accumulator from 16-bit to 32-bit and refuses operations that would cause the DACL size to exceed the 64K limit by returning an error. Users should apply the official kernel updates that address this issue to prevent DACL corruption.
Description
A vulnerability in the Linux kernel's SMB client affects the handling of Discretionary Access Control Lists (DACLs) when the new DACL exceeds 64K in size. The issue arises due to a 16-bit accumulator wrapping when calculating the size of the DACL, causing corruption of the DACL data sent to the server. This flaw is fixed by changing the internal size accumulator to 32-bit and refusing operations that would overflow the allowed DACL size.
References
- ubuntu.com/security/CVE-2026-97559 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-97559 (opens in a new tab)
- git.kernel.org/stable/c/d05045177a855386bca5e1909e08d06290e6e3b3 (opens in a new tab)
- git.kernel.org/stable/c/ee13d687d06a6fbb2008625dd560c654231b28e0 (opens in a new tab)
- git.kernel.org/stable/c/2ef532a01f44687f5b95001e88247cf05bff9892 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-97559 (opens in a new tab)
- git.kernel.org/stable/c/d433376abc47e10870ae732f89c7c1a60b199a0c (opens in a new tab)