CVE-2026-99275: Linux kernel · smb: client: reject short SESSION_SETUP responses
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 10 Nov 2026, 07:11 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
Thin evidence
One scorer or noneExploitation evidence
Disclosed: evidence found.
CVE published 7 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 9 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10linuxpkg:deb/ubuntu/linux?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-oraclepkg:deb/ubuntu/linux-oracle?arch=source&distro=stonkingOther 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
Until a fix is applied, avoid connecting to untrusted SMB2 servers or restrict SMB client access to trusted networks to reduce exposure.
Description
CVE-2026-99275 is a vulnerability in the Linux kernel SMB client where short SESSION_SETUP responses are improperly accepted. This flaw allows the parser to read stale buffer data, potentially leaking up to about 64 KB of memory from beyond the intended receive buffer. The issue affects multiple stable kernel versions and was reproduced on version 6.6.87.2. The vulnerability arises from insufficient validation of the SecurityBufferOffset and SecurityBufferLength fields in SMB2 SESSION_SETUP responses.