Regex DoS from a malicious server enrolled in Desktop
Priority LOW 25CWE-400Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- High
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-400.
Summary
Mattermost fails to properly validate a RegExp built off the server URL path, allowing an attacker in control of an enrolled server to mount a Denial Of Service.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00596 48th percentileScored 2026-11-07
Fix Fixed Mattermost Desktop (Mattermost): 5.5.1
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 Desktop | up to 5.5.0 | 5.5.1 | Patch available | CNA |
- Mattermost Desktop VendorMattermost Affected up to 5.5.0 Fixed in 5.5.1 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:mattermost:mattermost_desktop:*:*:*:*:*:*:*:* | before 5.5.1 | Vulnerable | Mattermost |
- cpe:2.3:a:mattermost:mattermost_desktop:*:*:*:*:*:*:*:* Versions before 5.5.1 Vulnerable ·Mattermost
Remediation
- Fix · CNA Mattermost Desktop (Mattermost) Fixed in 5.5.1
Timeline
- 2026-10-02 Threatist record created from CVE-2023-5876
- 2026-10-03 Alias added: GHSA-p8hg-mm67-hmp8
References
Advisory 1
More Mattermost Desktop vulnerabilities
- TI-2019-15074 An issue was discovered in Mattermost Desktop App before 4.3.0 on macOS. CVSS 3.1CRITICAL 9.8
- TI-2016-09099 An issue was discovered in Mattermost Desktop App before 3.4.0. CVSS 3.1CRITICAL 9.8
- TI-2019-15079 An issue was discovered in Mattermost Desktop App before 4.2.2. CVSS 3.1HIGH 8.8
- TI-2024-26542 RCE in desktop app in Windows by local attacker CVSS 3.1HIGH 7.8
- TI-2026-05712 Mattermost Desktop App fails to restrict the allow list of domains which NTLM credentials are passed CVSS 3.1HIGH 7.7
- TI-2026-00781 Arbitrary application execution via unvalidated server-controlled URLs in Help menu CVSS 3.1HIGH 7.6
Sources
- CVE-2023-5876 · CVE Program
- CVE-2023-5876 · NVD
- FIRST EPSS
- GHSA-p8hg-mm67-hmp8 · GitHub Advisory Database · CC BY 4.0
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