CVE-2026-97555: Linux kernel · smb: client: fix heap overflow in DACL owner/group rewrite
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 8.8 High.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:HExploitation 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 properly allocates buffer size for the rewritten DACL to prevent heap overflow. Users should apply the updated Linux kernel versions that include this patch. Since this is a kernel-level vulnerability, upgrading to patched kernel releases is the recommended remediation.
Description
A heap overflow vulnerability in the Linux kernel's SMB client was fixed. The flaw occurs during rewriting of Discretionary Access Control List (DACL) owner/group SIDs, where the buffer allocation does not account for the maximum possible size of replacement SIDs, leading to an overflow. This issue was detected by Kernel Address Sanitizer (KASAN) and affects specific Linux kernel versions. The vulnerability has a high CVSS score of 8.8, indicating significant confidentiality, integrity, and availability impact.
References
- ubuntu.com/security/CVE-2026-97555 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-97555 (opens in a new tab)
- git.kernel.org/stable/c/fb736ab4fb8c4fdb8b2f9ccd3a62e03d11549ca1 (opens in a new tab)
- git.kernel.org/stable/c/0ee150794c75bcd0be0e24ff3394f433cbae18cc (opens in a new tab)
- git.kernel.org/stable/c/2a9aee9ef5622d58d8aafaa3263b3ffe70e2d9dd (opens in a new tab)
- git.kernel.org/stable/c/7fa84c9ca690643f429ae2709584a47e74b572c9 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-97555 (opens in a new tab)
- git.kernel.org/stable/c/d5cea6766ae1868a51c7d17d77d065b4f55c587f (opens in a new tab)