VDB-351244 · CVE-2026-2457 · GCVE-0-2026-2457

Mattermost up to 10.11.10/11.2.2/11.3.0 API Endpoint origin validation

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
4.2	$0-$5k	0.00

Summaryinfo

A vulnerability described as problematic has been identified in Mattermost up to 10.11.10/11.2.2/11.3.0. This vulnerability affects unknown code of the component API Endpoint. Executing a manipulation can lead to origin validation. The identification of this vulnerability is CVE-2026-2457. The attack may be launched remotely. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as problematic was found in Mattermost up to 10.11.10/11.2.2/11.3.0. This vulnerability affects an unknown code block of the component API Endpoint. The manipulation with an unknown input leads to a origin validation vulnerability. The CWE definition for the vulnerability is CWE-346. The product does not properly verify that the source of data or communication is valid. As an impact it is known to affect integrity. CVE summarizes:

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to sanitize client-supplied post metadata which allows an authenticated attacker to spoof permalink embeds impersonating other users via crafted PUT requests to the post update API endpoint.. Mattermost Advisory ID: MMSA-2025-00569

The weakness was shared by daw10. The advisory is shared for download at mattermost.com. This vulnerability was named CVE-2026-2457 since 02/13/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are neither technical details nor an exploit publicly available.

Upgrading to version 10.11.11, 11.2.3, 11.3.1 or 11.4.0 eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Groupware Software

Name

Mattermost

Version

License

open-source

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

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

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

Exploitinginfo

Class: Origin validation
CWE: CWE-346 / CWE-345
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Mattermost 10.11.11/11.2.3/11.3.1/11.4.0

Timelineinfo

02/13/2026 CVE reserved
03/16/2026 +31 days Advisory disclosed
03/16/2026 +0 days VulDB entry created
03/20/2026 +4 days VulDB entry last update

Sourcesinfo

Advisory: mattermost.com
Researcher: daw10
Status: Confirmed

CVE: CVE-2026-2457 (🔒)
GCVE (CVE): GCVE-0-2026-2457
GCVE (VulDB): GCVE-100-351244

Entryinfo

Created: 03/16/2026 14:49
Updated: 03/20/2026 23:45
Changes: 03/16/2026 14:49 (64), 03/20/2026 23:45 (1)
Complete: 🔍
Cache ID: 216::103