CVE-2026-6517

highpriority · track · 31EPSS 0.002 · 8 %ileEUUS
grimoire priorityP2 · Scheduled
Exploitable?
—
no known exploitation
Likely / severe?
0.19% (8th) EPSS
CVSS 7.7 · high
Is it mine?
3 products
Check your exposure
Who says so?
3 sources
cnnvd · enisa_euvd · nvd

EPSS · scored 2026-10-28

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

01

cvss

Technical severity, 0–10. One row per scoring source.

7.7
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.3–7.7

v3.17.7highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:Nprimary · NVD / NIST USexploitability 3.1 · impact 4
v3.16.3mediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:Nsecondary · ENISA EU
v3.16.3mediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:Nsecondary · responsibledisclosure@mattermost.comexploitability 1.8 · impact 4
v3.17.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N/E:Usecondary · CVSS-BT (t0sche)
02

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-522US
04

affected products (3)

Products and version ranges known to be affected.

05

also known as (3)

Other names and identifiers for this entity.

06

sources

Which sources assert this record, and when.

cnnvdenisa_euvdnvdNVDCVE.orgMITRE
published 2026-06-15modified 2026-06-17
07

references (3)

External citations — patches, advisories, analysis.

scry

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