CVE-2026-4635 (GCVE-0-2026-4635)
Vulnerability from cvelistv5 – Published: 2026-05-22 10:28 – Updated: 2026-05-22 12:06
VLAI
Title
Persistent notification timing attack causing server denial of service
Summary
Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to archive the channel before removing persistent notifications which allows authenticated user to crash the server via timing the creation of persistent notification message between the server deleting existing persistent notifications and archiving the channel.. Mattermost Advisory ID: MMSA-2026-00637
Severity
6.5 (Medium)
CWE
- CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.6.0 , ≤ 11.6.0
(semver)
Affected: 11.5.0 , ≤ 11.5.3 (semver) Affected: 11.4.0 , ≤ 11.4.4 (semver) Affected: 10.11.0 , ≤ 10.11.14 (semver) Unaffected: 11.7.0 Unaffected: 11.6.1 Unaffected: 11.5.4 Unaffected: 11.4.5 Unaffected: 10.11.15 |
Credits
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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