Mattermost up to 10.11.14/11.4.4/11.5.3/11.6.0 resource consumption

Summaryinfo

A vulnerability categorized as problematic has been discovered in Mattermost up to 10.11.14/11.4.4/11.5.3/11.6.0. The affected element is an unknown function. The manipulation results in resource consumption. This vulnerability is cataloged as CVE-2026-5308. The attack may be launched remotely. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic has been found in Mattermost up to 10.11.14/11.4.4/11.5.3/11.6.0. Affected is an unknown functionality. The manipulation with an unknown input leads to a resource consumption vulnerability. CWE is classifying the issue as CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. This is going to have an impact on availability. CVE summarizes:

Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to enforce request body size limits on plugin HTTP endpoints which allows an attacker to cause a denial of service via crafted oversized HTTP requests.. Mattermost Advisory ID: MMSA-2026-00646

The weakness was shared by thecybertantrik. The advisory is shared for download at mattermost.com. This vulnerability is traded as CVE-2026-5308 since 04/01/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. Additional levels of successful authentication are needed for exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 10.11.15, 11.4.5, 11.5.4, 11.6.1 or 11.7.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-1243). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

• Mattermost Mattermost

Productinfo

Type

• Groupware Software

Name

• Mattermost

Version

• 10.11.0
• 10.11.1
• 10.11.2
• 10.11.3
• 10.11.4
• 10.11.5
• 10.11.6
• 10.11.7
• 10.11.8
• 10.11.9
• 10.11.10
• 10.11.11
• 10.11.12
• 10.11.13
• 10.11.14
• 11.0
• 11.1
• 11.2
• 11.3
• 11.4
• 11.4.0
• 11.4.1
• 11.4.2
• 11.4.3
• 11.4.4
• 11.5
• 11.5.0
• 11.5.1
• 11.5.2
• 11.5.3
• 11.6.0

License

• open-source

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Discussion