VulnerabilityPublished 7 Nov 2026

CVE-2026-99278: Linux kernel · ksmbd: limit sessions on each connection

Source GCVE Database

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Authoritative record:CVE-2026-99278· Medium

Not known to be exploited · fixed in dc6aa1ba8b7fff8800ad9bf143f17d308e02ec68 : update Linux kernel when convenient.

Data as of 7 Nov 2026, 16:17 UTC

Severity

Medium

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

Thin evidence

One scorer or none

Patch: Available – fixed in dc6aa1ba8b7fff8800ad9bf143f17d308e02ec68, 94f8462fc9d5332bc54e91605003c17381e9171a, 7.3

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.

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What to do

Upgrade Linux kernel to dc6aa1ba8b7fff8800ad9bf143f17d308e02ec68, 94f8462fc9d5332bc54e91605003c17381e9171a or 7.3.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=7.2.8 <7.3	Fixed in dc6aa1ba8b7fff8800ad9bf143f17d308e02ec68 94f8462fc9d5332bc54e91605003c17381e9171a 7.3
LinuxLinux	Affected =7.3	Fixed in–

AI-suggested

A fix has been implemented in the Linux kernel ksmbd component that enforces a maximum number of sessions per connection, defaulting to 64, and properly manages connection slot reservations during authentication. Users should apply the official kernel update containing this patch to remediate the vulnerability.

Description

A vulnerability in the Linux kernel's ksmbd component allowed clients to create an unbounded number of valid SMB sessions on a single connection by repeatedly completing authentication, due to improper session limit enforcement. The issue has been addressed by reserving connection slots before session allocation and enforcing a configurable maximum sessions per connection, defaulting to 64. The fix also exposes this limit via procfs and maintains compatibility with existing request formats.

Impact

Clients could exploit this vulnerability to create an unlimited number of valid SMB sessions on a single connection, potentially leading to resource exhaustion or denial of service conditions on the server handling ksmbd. This could degrade server performance or availability.

Summary

The Linux kernel's ksmbd module had a flaw where the pending setup limit only counted sessions in progress, allowing a client to repeatedly authenticate and accumulate an unlimited number of valid sessions on one connection. The patch reserves a connection slot before allocating a session and retains a connection reference during authentication. The first SMB3 channel uses this reservation, and reauthentication reuses it. Slots are returned on allocation failure, channel removal, or session destruction. A max_sessions_per_connection parameter is introduced, defaulting to 64 for compatibility, and exposed via procfs. Existing connection limits still bound the total number of sessions globally.

References

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