EUVD-2026-12405
GHSA-m5rv-56xx-hfc6
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Primary rating from NVD.
CVSS VectorNVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Lifecycle Timeline
4DescriptionCVE.org
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly handle very long passwords, which allows an attacker to overload the server CPU and memory via executing login attempts with multi-megabyte passwords. Mattermost Advisory ID: MMSA-2026-00587
AnalysisAI
Mattermost 10.11.x through 11.3.x fails to validate password length, allowing unauthenticated attackers to trigger denial of service by submitting multi-megabyte passwords during login attempts that consume excessive CPU and memory resources. The vulnerability affects all versions up to 10.11.10, 11.2.2, and 11.3.0, with no patch currently available.
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Mattermost versions 11.3.0 or earlier, 11.2.2 or earlier, or 10.11.10 or earlier with publicly accessible login endpoint. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | This vulnerability presents a moderate-to-high real-world risk based on multiple factors. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker identifies an internet-facing Mattermost server and crafts malicious login requests containing passwords of several megabytes in size. By automating these requests from multiple sources or in rapid succession, the attacker forces the server to allocate significant CPU cycles and memory to process each oversized password through the authentication system, eventually exhausting server resources and causing legitimate users to experience service outages or degraded performance. |
| Remediation | Organizations should immediately upgrade affected Mattermost installations to patched versions: upgrade from 11.3.0 to 11.3.1 or later, from 11.2.2 to 11.2.3 or later, or from 10.11.10 to 10.11.11 or later. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Inventory all Mattermost instances and confirm version numbers; enable login attempt rate limiting and IP-based throttling. …
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View allVendor StatusVendor
SUSE
Severity: High| Product | Status |
|---|---|
| openSUSE Leap 15.6 | Fixed |
| SUSE Linux Enterprise Module for Package Hub 15 SP5 | Fixed |
| SUSE Linux Enterprise Module for Package Hub 15 SP6 | Fixed |
| openSUSE Leap 15.5 | Fixed |
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External POC / Exploit Code
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