Logo
-

Byte Open Security

(ByteOS Network)

Log In

Sign Up

ByteOS

Security
Vulnerability Details
Registries
Custom Views
Weaknesses
Attack Patterns
Filters & Tools
NVD Vulnerability Details :
CVE-2026-5163
Analyzed
More InfoOfficial Page
Source-responsibledisclosure@mattermost.com
View Known Exploited Vulnerability (KEV) details
Published At-18 May, 2026 | 09:16
Updated At-18 May, 2026 | 19:12

Mattermost versions 11.5.x <= 11.5.1 fail to verify channel membership when processing AI-assisted message rewrites which allows an authenticated attacker to read the content of threads in private channels and direct messages they do not have access to via a crafted request to the post rewrite endpoint.. Mattermost Advisory ID: MMSA-2026-00645

CISA Catalog
Date AddedDue DateVulnerability NameRequired Action
N/A
Date Added: N/A
Due Date: N/A
Vulnerability Name: N/A
Required Action: N/A
Metrics
TypeVersionBase scoreBase severityVector
Secondary3.16.5MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Type: Secondary
Version: 3.1
Base score: 6.5
Base severity: MEDIUM
Vector:
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
CPE Matches
Mattermost, Inc.
mattermost
>>mattermost_server>>Versions from 11.5.0(inclusive) to 11.5.2(exclusive)
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Weaknesses
CWE IDTypeSource
CWE-862Secondaryresponsibledisclosure@mattermost.com
CWE ID: CWE-862
Type: Secondary
Source: responsibledisclosure@mattermost.com
Evaluator Description
Evaluator Impact

Evaluator Solution

Vendor Statements
References
HyperlinkSourceResource
https://mattermost.com/security-updatesresponsibledisclosure@mattermost.com
Vendor Advisory
Hyperlink: https://mattermost.com/security-updates
Source: responsibledisclosure@mattermost.com
Resource:
Vendor Advisory
Change History
0Changes found
Details not found