CVE-2026-90169: Linux kernel · ksmbd: free preauth sessions on connection teardown
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 26 Oct 2026, 13:47 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 14% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Exploitation evidence
Disclosed: evidence found.
CVE published 17 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 for this vulnerability is available in the Linux kernel. Users should apply the official kernel updates that address this issue to ensure that preauthentication sessions are properly freed on connection teardown. Since this is a kernel-level fix, upgrading to the patched kernel versions is the recommended remediation.
Description
A vulnerability in the Linux kernel's ksmbd SMB3.1.1 multichannel implementation allows preauthentication session objects to remain allocated if a client disconnects before completing authentication. This occurs because the preauthentication session is not freed on connection teardown if the client disconnects after the NTLM negotiate request but before the authenticate request. The issue has been resolved by ensuring that any remaining preauthentication sessions are released when tearing down the connection and initializing the session list safely during connection allocation.
References
- ubuntu.com/security/CVE-2026-90169 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-90169 (opens in a new tab)
- git.kernel.org/linus/06c7b1d731bc105a8644f1b70165ba8b9416cbab (opens in a new tab)
- msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-90169.json (opens in a new tab)
- support.microsoft.com/lifecycle (opens in a new tab)
- first.org/cvss (opens in a new tab)