Collapsed Reply Threads APIs leak message contents from private channels
Priority LOW 30CWE-862Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-862.
Summary
Mattermost fails to check channel membership when accessing message threads, allowing an attacker to access arbitrary posts by using the message threads API.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0054 45th percentileScored 2026-11-07
Fix Fixed Mattermost (Mattermost): 7.9.3, 7.8.4, 7.1.9 +1
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 | up to 7.9.3; up to 7.8.4; up to 7.1.9; 7.10.0 | 7.9.3, 7.8.4, 7.1.9, 7.10.1 | Patch available | CNA |
- Mattermost VendorMattermost Affected up to 7.9.3; up to 7.8.4; up to 7.1.9; 7.10.0 Fixed in 7.9.3, 7.8.4, 7.1.9, 7.10.1 Patch available CNA
CPE configurations NVD · 2
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mattermost:mattermost:*:*:*:*:*:*:*:* | 7.1.0 – 7.1.9; 7.8.0 – 7.8.4; 7.9.0 – 7.9.3 | Vulnerable | Mattermost |
| cpe:2.3:a:mattermost:mattermost:7.10.0:*:*:*:*:*:*:* | 7.10.0 | Vulnerable | Mattermost |
- cpe:2.3:a:mattermost:mattermost:*:*:*:*:*:*:*:* Versions 7.1.0 – 7.1.9; 7.8.0 – 7.8.4; 7.9.0 – 7.9.3 Vulnerable ·Mattermost
- cpe:2.3:a:mattermost:mattermost:7.10.0:*:*:*:*:*:*:* Versions 7.10.0 Vulnerable ·Mattermost
Remediation
- Fix · CNA Mattermost (Mattermost) Fixed in 7.9.3, 7.8.4, 7.1.9, 7.10.1
Timeline
- 2026-10-02 Threatist record created from CVE-2023-2787
- 2026-10-03 Alias added: GHSA-8m2w-p6c5-hh6c
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-2023-2787 · CVE Program
- CVE-2023-2787 · NVD
- FIRST EPSS
- GHSA-8m2w-p6c5-hh6c · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences