Mattermost up to 10.11.10/11.2.2/11.3.0 POST Request authorization

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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4.2$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as problematic, was found in Mattermost up to 10.11.10/11.2.2/11.3.0. The impacted element is an unknown function of the component POST Request Handler. Such manipulation leads to authorization. This vulnerability is listed as CVE-2026-4265. The attack may be performed from remote. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Mattermost up to 10.11.10/11.2.2/11.3.0 and classified as problematic. Affected by this issue is some unknown functionality of the component POST Request Handler. The manipulation with an unknown input leads to a authorization vulnerability. Using CWE to declare the problem leads to CWE-863. The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions. Impacted is 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 validate team-specific upload_file permissions which allows a guest user to post files in channels where they lack upload_file permission via uploading files in a team where they have permission and reusing the file metadata in a POST request to a different team. Mattermost Advisory ID: MMSA-2025-00553

The weakness was presented by 0x7oda7123. The advisory is shared for download at mattermost.com. This vulnerability is handled as CVE-2026-4265 since 03/16/2026. The exploitation is known to be easy. The attack may be launched 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.

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

Exploitinginfo

Class: Authorization
CWE: CWE-863 / CWE-285 / CWE-266
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 10.11.11/11.2.3/11.3.1/11.4.0

Timelineinfo

03/16/2026 Advisory disclosed
03/16/2026 +0 days CVE reserved
03/16/2026 +0 days VulDB entry created
03/21/2026 +5 days VulDB entry last update

Sourcesinfo

Advisory: mattermost.com
Researcher: 0x7oda7123
Status: Confirmed

CVE: CVE-2026-4265 (🔒)
GCVE (CVE): GCVE-0-2026-4265
GCVE (VulDB): GCVE-100-351248

Entryinfo

Created: 03/16/2026 14:50
Updated: 03/21/2026 11:03
Changes: 03/16/2026 14:50 (64), 03/21/2026 11:03 (1)
Complete: 🔍
Cache ID: 216::103

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