CVE-2026-5755
Last modified
CVE-2026-5755 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.2, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate the TIFF IFD offset in the image header before allocating memory, which allows authenticated users with file upload or posting permissions to cause a denial of service (server OOM) via uploading a crafted TIFF file or posting a URL that serves one.. Mattermost Advisory ID: MMSA-2026-00648. EPSS estimates a 0.24% chance of exploitation in the next 30 days.
Description
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.2, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to validate the TIFF IFD offset in the image header before allocating memory, which allows authenticated users with file upload or posting permissions to cause a denial of service (server OOM) via uploading a crafted TIFF file or posting a URL that serves one.. Mattermost Advisory ID: MMSA-2026-00648
Metrics
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mattermost | Mattermost Server | >= 10.11.0, < 10.11.15 |
| Mattermost | Mattermost Server | >= 11.4.0, < 11.4.5 |
| Mattermost | Mattermost Server | >= 11.5.0, < 11.5.3 |
| Mattermost | Mattermost Server | >= 11.6.0, < 11.6.1 |
References
- https://mattermost.com/security-updatesVendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-5755?
How severe is CVE-2026-5755?
How do I fix CVE-2026-5755?
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- 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-2026-57532Malicious HTML content contained in the layout specification…8.8
- CVE-2026-57533Malicious HTML content could be injected into the page preti…2.1
- CVE-2026-57534Malicious HTML content could be injected into the content of…2.1
- CVE-2026-57535Content injected to PDF rendering contexts could, in many pl…2.1
- CVE-2026-57536Our payment integration with Mollie did not properly validat…6.3
- CVE-2026-5754Reflected Cross-Site Scripting (XSS) Vulnerability in Radwar…6.1
- CVE-2026-5756Unauthenticated Configuration File Modification Vulnerabilit…7.5
- CVE-2026-5757Unauthenticated remote information disclosure vulnerability …7.5
- CVE-2026-57571Crawl4AI is an open-source LLM-friendly web crawler and scra…9.6
- CVE-2026-57572Crawl4AI is an open-source LLM-friendly web crawler and scra…10
- CVE-2026-57573Crawl4AI is an open-source LLM-friendly web crawler and scra…8.6
- CVE-2026-57574Misskey is an open source, federated social media platform. …7.4
Are you affected by CVE-2026-5755?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST