Mattermost up to 10.11.14/11.4.4/11.5.3/11.6.0 PR Details Endpoint improper validation of specified type of input

CVSS Meta Temp Score
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CTI Interest Score
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4.2$0-$5k0.00

Summaryinfo

A vulnerability identified as problematic has been detected in Mattermost up to 10.11.14/11.4.4/11.5.3/11.6.0. The impacted element is an unknown function of the component PR Details Endpoint. This manipulation causes improper validation of specified type of input. This vulnerability is registered as CVE-2026-4646. Remote exploitation of the attack is possible. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Mattermost up to 10.11.14/11.4.4/11.5.3/11.6.0. Affected by this vulnerability is some unknown functionality of the component PR Details Endpoint. The manipulation with an unknown input leads to a improper validation of specified type of input vulnerability. The CWE definition for the vulnerability is CWE-1287. The product receives input that is expected to be of a certain type, but it does not validate or incorrectly validates that the input is actually of the expected type. As an impact it is known to affect availability. The summary by CVE is:

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 validate user-supplied input in API request handlers which allows an authenticated attacker to crash the plugin process via a crafted HTTP request to the PR details endpoint.. Mattermost Advisory ID: MMSA-2026-00638

The weakness was published by Mariusz Maik. The advisory is shared at mattermost.com. This vulnerability is known as CVE-2026-4646 since 03/23/2026. The exploitation appears to be easy. The attack can be launched remotely. Neither technical details nor an exploit are publicly available.

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-2026-1173). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Mattermost Mattermost

Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.3
VulDB Meta Temp Score: 4.2

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 4.3
CNA Vector (Mattermost): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Improper validation of specified type of input
CWE: CWE-1287 / CWE-20
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Mattermost 10.11.15/11.4.5/11.5.4/11.6.1/11.7.0

Timelineinfo

03/23/2026 CVE reserved
05/22/2026 +59 days Advisory disclosed
05/22/2026 +0 days VulDB entry created
05/25/2026 +3 days VulDB entry last update

Sourcesinfo

Advisory: mattermost.com
Researcher: Mariusz Maik
Status: Confirmed

CVE: CVE-2026-4646 (🔒)
GCVE (CVE): GCVE-0-2026-4646
GCVE (VulDB): GCVE-100-365185
CERT Bund: WID-SEC-2026-1173 - Mattermost: Mehrere Schwachstellen erm&ouml;glichen nicht spezifizierten Angriff

Entryinfo

Created: 05/22/2026 14:12
Updated: 05/25/2026 23:05
Changes: 05/22/2026 14:12 (64), 05/25/2026 23:05 (7)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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