Channel IDs of archived/restored channels leaked via webhook events
Priority LOW 24CWE-200Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- Low · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-200.
Summary
Mattermost versions 9.5.x <= 9.5.5 and 9.8.0 fail to properly sanitize the recipients of a webhook event which allows an attacker monitoring webhook events to retrieve the channel IDs of archived or restored channels.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00345 28th percentileScored 2026-11-07
Fix Fixed Mattermost (Mattermost): 9.9.0, 9.8.1, 9.5.6
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Mattermost | Mattermost | 9.8.0; 9.5.0 – 9.5.5 | 9.9.0, 9.8.1, 9.5.6 | Patch available | CNA |
- Mattermost VendorMattermost Affected 9.8.0; 9.5.0 – 9.5.5 Fixed in 9.9.0, 9.8.1, 9.5.6 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mattermost:mattermost:*:*:*:*:*:*:*:* | 9.5.0 to before 9.5.6; 9.8.0 to before 9.8.1 | Vulnerable | Mattermost |
- cpe:2.3:a:mattermost:mattermost:*:*:*:*:*:*:*:* Versions 9.5.0 to before 9.5.6; 9.8.0 to before 9.8.1 Vulnerable ·Mattermost
Remediation
- Fix · CNA Mattermost (Mattermost) Fixed in 9.9.0, 9.8.1, 9.5.6
Timeline
- 2026-10-02 Threatist record created from CVE-2024-39807
- 2026-10-03 Alias added: GHSA-fc2h-j9fj-rh35
References
Advisory 1
More Mattermost vulnerabilities
- TI-2024-26695 Malicious remote can invite itself to an arbitrary local channel CVSS 3.1CRITICAL 9.6
- TI-2023-02056 Oauth authorization codes do not expire when deauthorizing an oauth2 app CVSS 3.1CRITICAL 9.1
- TI-2019-15069 An issue was discovered in Mattermost Mobile Apps before 1.26.0. CVSS 3.1CRITICAL 9.1
- TI-2024-26233 Malicious remote can add users to arbitrary teams and channels CVSS 3.1HIGH 8.7
- TI-2024-26746 Permanently local data deletion by malicious remote CVSS 3.1HIGH 8.7
- TI-2023-06508 Injection in Mattermost CVSS 3.1HIGH 8.8
Sources
- CVE-2024-39807 · CVE Program
- CVE-2024-39807 · NVD
- FIRST EPSS
- GHSA-fc2h-j9fj-rh35 · GitHub Advisory Database · CC BY 4.0
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