VulnerabilityPublished 7 Nov 2026

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

Source GCVE Database

Authoritative record:CVE-2026-99275· High

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

Data as of 7 Nov 2026, 16:05 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

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 7 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-w3q4-mjfj-h6cq

What to do

Upgrade Linux kernel to df63e01933886153e40706483b9635b2456ad91f or 4d8930afa3446041358a7db33e7b23a0bb9459b5.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 5478f9ba9a34d660eb3227dcd16314689c51f946, < df63e01933886153e40706483b9635b2456ad91f	Fixed in df63e01933886153e40706483b9635b2456ad91f
LinuxLinux	Affected ≥ 5478f9ba9a34d660eb3227dcd16314689c51f946, < 4d8930afa3446041358a7db33e7b23a0bb9459b5	Fixed in 4d8930afa3446041358a7db33e7b23a0bb9459b5
LinuxLinux	Affected =3.6	Fixed in–

AI-suggested

A fix has been implemented in the Linux kernel to reject short SESSION_SETUP responses and validate buffer lengths before processing. Users should apply the official kernel updates that include this fix. Since this is a kernel vulnerability, updating to a patched kernel version is the recommended remediation. No alternative mitigations or workarounds are indicated in the advisory.

Description

A vulnerability in the Linux kernel SMB client allows acceptance of short SESSION_SETUP responses that lack required fields. This causes the parser to read stale data from a reused buffer, potentially leaking up to about 64 KB of memory back to the server during NTLMv2 authentication. The issue affects all supported stable kernel trees and was reproduced on version 6.6.87.2. The vulnerability has been resolved by rejecting short SESSION_SETUP responses and validating buffer lengths before processing.

References

Community reviews

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