CVE-2026-2455
Last modified
CVE-2026-2455 is a medium-severity vulnerability rated 4.3/10 on the CVSS scale. Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation which allows an attacker to perform SSRF attacks against internal services via IPv4-mapped IPv6 literals (e.g., [::ffff:127.0.0.1]).. Mattermost Advisory ID: MMSA-2026-00585. EPSS estimates a 0.17% chance of exploitation in the next 30 days.
Description
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation which allows an attacker to perform SSRF attacks against internal services via IPv4-mapped IPv6 literals (e.g., [::ffff:127.0.0.1]).. Mattermost Advisory ID: MMSA-2026-00585
Metrics
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mattermost | Mattermost Server | >= 10.11.0, < 10.11.11 |
| Mattermost | Mattermost Server | >= 11.2.0, < 11.2.3 |
| Mattermost | Mattermost Server | >= 11.3.0, < 11.3.1 |
References
- https://mattermost.com/security-updatesVendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-2455?
How severe is CVE-2026-2455?
How do I fix CVE-2026-2455?
How Strix Helps
- One Click Account Takeover in GranolaHow a notification link broke out of Electron and led to a one-click account takeover.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
Related CVEs from 2026
- CVE-2026-24544Missing Authorization vulnerability in Harmonic Design HD Qu…4.3
- CVE-2026-24545Missing Authorization vulnerability in Nikki Blight QR Redir…4.3
- CVE-2026-24546Missing Authorization vulnerability in Ruben Garcia GamiPres…5.3
- CVE-2026-24547Unauthenticated Broken Access Control in SiteGround Email Ma…5.3
- CVE-2026-24548Server-Side Request Forgery (SSRF) vulnerability in princeah…5.4
- CVE-2026-24549Cross-Site Request Forgery (CSRF) vulnerability in Paolo Geo…4.3
- CVE-2026-24550Improper Neutralization of Input During Web Page Generation …6.5
- CVE-2026-24551Missing Authorization vulnerability in monetagwp Monetag Off…5.4
- CVE-2026-24552Improper Neutralization of Special Elements used in an SQL C…8.5
- CVE-2026-24553Exposure of Sensitive System Information to an Unauthorized …4.3
- CVE-2026-24554Cross-Site Request Forgery (CSRF) vulnerability in Convers L…4.3
- CVE-2026-24555Improper Neutralization of Input During Web Page Generation …6.5
Are you affected by CVE-2026-2455?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST