Linux Kernel up to 7.3.1 ksmbd allocation of resources

Summaryinfo

A vulnerability was found in Linux Kernel up to 7.3.1. It has been rated as critical. This affects an unknown part of the component ksmbd. Performing a manipulation results in allocation of resources. This vulnerability is identified as CVE-2026-99278. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 7.3.1. This affects an unknown function of the component ksmbd. The manipulation with an unknown input leads to a allocation of resources vulnerability. CWE is classifying the issue as CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. This is going to have an impact on availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: ksmbd: limit sessions on each connection The pending setup limit only counts InProgress sessions. A client can complete authentication repeatedly and retain an unbounded number of Valid sessions on one connection. Reserve a connection slot before allocating a session and retain a connection reference while authentication is in progress. The first SMB3 channel takes over that reservation; binding to another connection reserves one slot there. Reauthentication and authentication continuation reuse the existing reservation. Return slots on allocation or insertion failure, channel removal, and final session destruction. Accept max_sessions_per_connection in reserved startup-request space and default to 64 when older tools leave it zero. Keep the request size and existing field offsets unchanged. Expose the configured limit in procfs. The existing connection limits bound the aggregate number of sessions without a separate global session allocation limit.

The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-99278 since 09/25/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 11/07/2026). MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading to version 7.3.2 or 7.4-rc1 eliminates this vulnerability. Applying the patch 94f8462fc9d5332bc54e91605003c17381e9171a/dc6aa1ba8b7fff8800ad9bf143f17d308e02ec68 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.3.0
• 7.3.1

License

• open-source

Website

• Vendor: https://www.kernel.org/

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