Mattermost up to 10.11.6/10.12.2/11.0.4 WebSocket Request Field improper validation of specified type of input

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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5.3$0-$5k0.00

Summaryinfo

A vulnerability classified as problematic has been found in Mattermost up to 10.11.6/10.12.2/11.0.4. This vulnerability affects unknown code of the component WebSocket Request Field Handler. This manipulation causes improper validation of specified type of input. This vulnerability is handled as CVE-2025-12689. The attack can be initiated remotely. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Mattermost up to 10.11.6/10.12.2/11.0.4. It has been declared as problematic. Affected by this vulnerability is some unknown processing of the component WebSocket Request Field Handler. 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 11.0.x <= 11.0.4, 10.12.x <= 10.12.2, 10.11.x <= 10.11.6 fail to check WebSocket request field for proper UTF-8 format, which allows attacker to crash Calls plug-in via sending malformed request.

The advisory is shared at mattermost.com. This vulnerability is known as CVE-2025-12689 since 11/04/2025. The exploitation appears to be easy. The attack can be launched remotely. Neither technical details nor an exploit are publicly available.

Upgrading to version 10.11.7, 10.12.3, 11.0.5 or 11.1.0 eliminates this vulnerability.

The vulnerability is also documented in the databases at EUVD (EUVD-2025-203918) and CERT Bund (WID-SEC-2025-2880). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

  • Mattermost Mattermost

Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.4
VulDB Meta Temp Score: 5.3

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

CNA Base Score: 6.5
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 10.11.7/10.12.3/11.0.5/11.1.0

Timelineinfo

11/04/2025 CVE reserved
12/17/2025 +43 days Advisory disclosed
12/17/2025 +0 days VulDB entry created
02/27/2026 +72 days VulDB entry last update

Sourcesinfo

Advisory: mattermost.com
Status: Confirmed

CVE: CVE-2025-12689 (🔒)
GCVE (CVE): GCVE-0-2025-12689
GCVE (VulDB): GCVE-100-337021
EUVD: 🔒
CERT Bund: WID-SEC-2025-2880 - Mattermost Server und Desktop: Mehrere Schwachstellen

Entryinfo

Created: 12/17/2025 21:26
Updated: 02/27/2026 11:34
Changes: 12/17/2025 21:26 (63), 12/20/2025 20:21 (1), 02/27/2026 11:34 (7)
Complete: 🔍
Cache ID: 216::103

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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