Mattermost Desktop App up to 5.5.13/6.1.x insufficiently protected credentials

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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4.6$0-$5k4.14-

Summaryinfo

A vulnerability was found in Mattermost Desktop App up to 5.5.13/6.1.x. It has been declared as problematic. This affects an unknown part. Such manipulation leads to insufficiently protected credentials. This vulnerability is uniquely identified as CVE-2026-6517. The attack can be launched remotely. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Mattermost Desktop App up to 5.5.13/6.1.x and classified as problematic. Affected by this issue is some unknown processing. The manipulation with an unknown input leads to a insufficiently protected credentials vulnerability. Using CWE to declare the problem leads to CWE-522. The product transmits or stores authentication credentials, but it uses an insecure method that is susceptible to unauthorized interception and/or retrieval. Impacted is confidentiality. CVE summarizes:

Mattermost Desktop App versions <=6.1 5.5.13.0 fail to restrict the allow list of domains to which NTLM credentials were forwarded to in the Mattermost Desktop App which allows any user on a server without the image proxy enabled to intercept other users credentials via embedding an image that routes to an external web server. Mattermost Advisory ID: MMSA-2026-00651

The weakness was disclosed by falke. The advisory is available at mattermost.com. This vulnerability is handled as CVE-2026-6517 since 04/17/2026. The exploitation is known to be difficult. The attack may be launched remotely. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1552 by the MITRE ATT&CK project.

Upgrading to version 5.13.6.0 or 6.2.0 eliminates this vulnerability.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.7
VulDB Meta Temp Score: 4.6

VulDB Base Score: 3.1
VulDB Temp Score: 3.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 6.3
CNA Vector (Mattermost): 🔒

CVSSv2info

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

Exploitinginfo

Class: Insufficiently protected credentials
CWE: CWE-522
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
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: Desktop App 5.13.6.0/6.2.0

Timelineinfo

04/17/2026 CVE reserved
06/15/2026 +59 days Advisory disclosed
06/15/2026 +0 days VulDB entry created
06/15/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: mattermost.com
Researcher: falke
Status: Confirmed

CVE: CVE-2026-6517 (🔒)
GCVE (CVE): GCVE-0-2026-6517
GCVE (VulDB): GCVE-100-370922

Entryinfo

Created: 06/15/2026 16:58
Changes: 06/15/2026 16:58 (64)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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