CVE-2018-21249 An issue was discovered in Mattermost Server before 5.3.0.
Low 3.7
Published
Updated
Check this codebase for CVE-2018-21249 and fix it if it is affected.
What it is: CVE-2018-21249 is a low-severity vulnerability in Mattermost Mattermost Server, published on 19 Jun 2020.
Exploitation: There is no known exploitation of CVE-2018-21249 in the wild and no public exploit code.
Affected product: Mattermost Mattermost Server. No package-level version data is available, so check the vendor advisory linked from the reference page.
Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.
Reference: https://insights.sbomify.com/CVE-2018-21249/ (Markdown: https://insights.sbomify.com/CVE-2018-21249/index.md)
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2018-21249?
CVE-2018-21249 is a low-severity vulnerability in Mattermost Mattermost Server, published on 19 Jun 2020.
Official description
An issue was discovered in Mattermost Server before 5.3.0. It mishandles timing.
Which versions are affected by CVE-2018-21249?
It affects 1 product.
Products include Mattermost Mattermost Server.
How do I fix CVE-2018-21249?
No fix has been published for CVE-2018-21249 yet. Limit exposure of the affected software until one is available.
Is CVE-2018-21249 being exploited?
There is no known exploitation of CVE-2018-21249 in the wild and no public exploit code.
Other vulnerabilities in Mattermost Mattermost Server
- CVE-2025-12419 Account takeover on OAuth/OpenID-enabled servers
- CVE-2025-12421 Account Takeover via Code Exchange Endpoint
- CVE-2025-4981 Path Traversal Leading to RCE by Any Authenticated Mattermost User
- CVE-2025-20051 Arbitrary file read via block duplication in Mattermost Boards
- CVE-2025-25279 Arbitrary file read in Mattermost Boards via import & export board archive
Sources
Also known as GHSA-f3c7-479p-6gqx.