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VulnerabilityPublished

CVE-2026-99275: Linux kernel · smb: client: reject short SESSION_SETUP responses

Affects Linux kernelSource CVE Database V5

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Not known to be exploited : upgrade to df63e01933886153e40706483b9635b2456ad91f or 4d8930afa3446041358a7db33e7b23a0bb9459b5 soon.

Data as of 7 Nov 2026, 14:19 UTC

Severity
High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

Thin evidence

One scorer or none
Patch
Available – fixed in df63e01933886153e40706483b9635b2456ad91f, 4d8930afa3446041358a7db33e7b23a0bb9459b5

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 7 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 7 Nov 2026.

What to do

Upgrade Linux kernel to df63e01933886153e40706483b9635b2456ad91f or 4d8930afa3446041358a7db33e7b23a0bb9459b5.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 5478f9ba9a34d660eb3227dcd16314689c51f946, < df63e01933886153e40706483b9635b2456ad91f
Fixed in
  • df63e01933886153e40706483b9635b2456ad91f
LinuxLinuxAffected
  • ≥ 5478f9ba9a34d660eb3227dcd16314689c51f946, < 4d8930afa3446041358a7db33e7b23a0bb9459b5
Fixed in
  • 4d8930afa3446041358a7db33e7b23a0bb9459b5
LinuxLinuxAffected
  • =3.6
Fixed in–

AI-suggested

A fix is available and has been applied in the Linux kernel commits df63e01933886153e40706483b9635b2456ad91f and 4d8930afa3446041358a7db33e7b23a0bb9459b5. Users and administrators should update to a Linux kernel version including these commits or later to remediate this vulnerability.

Description

A vulnerability in the Linux kernel SMB client allows acceptance of short SESSION_SETUP responses that are too small to contain required fields. This leads to reading stale buffer data and copying up to about 64 KB of memory beyond the intended buffer, which is then sent back to the server during NTLMv2 authentication. The issue affects all supported stable Linux kernel trees and was reproduced on version 6.6.87.2. The vulnerability has been fixed in specific commits.

References

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