GitLabApplication
CVE-2021-39933
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedAn issue has been discovered in GitLab CE/EE affecting all versions starting from 12.10 before 14.3.6, all versions starting from 14.4 before 14.4.4, all versions starting from 14.5 before 14.5.2. A regular expression used for handling user input (notes, comments, etc) was susceptible to catastrophic backtracking that could cause a DOS attack.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA regular expression in GitLab used for parsing user input (notes, comments) is susceptible to catastrophic backtracking, enabling attackers to craft malicious input that causes excessive CPU consumption and denial of service through ReDoS (Regular Expression Denial of Service).
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
GitLabApplication
>= 12.10.0, < 14.3.6>= 14.4.0, < 14.4.4>= 14.5.0, < 14.5.2CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Determine installed GitLab versionRun `sudo gitlab-rake gitlab:env:info` or check the GitLab admin area dashboard for the version numberAffected if The version falls within these ranges: >= 12.10.0 and < 14.3.6, OR >= 14.4.0 and < 14.4.4, OR >= 14.5.0 and < 14.5.2
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Verify notes and comments are accessibleCheck if the GitLab instance has project or issue notes enabled by navigating to a project Settings or attempting to create a note on an issue/MRAffected if Notes and comments feature is enabled and accessible to users (the vulnerable regex only triggers when user-provided notes are processed)
An environment is affected if the installed GitLab version is within any of the three affected version ranges and notes/comments functionality is active, allowing malicious input to be submitted and processed by the vulnerable regex.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped14.3.614.4.414.5.2
Upgrade GitLab to version 14.3.6, 14.4.4, 14.5.2 or later to patch the vulnerable regular expression.
14.3.6, 14.4.4, or 14.5.2 (or later stable release)
- Backup your GitLab instance (database and Git repositories) before upgrading
- Stop the GitLab service
- For GitLab installations using Omnibus: run `gitlab-ctl stop`
- Upgrade to a fixed version: if currently on 12.10.x to 14.3.x, upgrade to 14.3.6; if on 14.4.x, upgrade to 14.4.4; if on 14.5.x to 14.5.1, upgrade to 14.5.2
- For Omnibus: use your package manager to install the new version (e.g., `apt-get update && apt-get install gitlab-ce` or `yum install gitlab-ce`)
- Reconfigure GitLab: run `gitlab-ctl reconfigure`
- Start GitLab: run `gitlab-ctl start`
- Verify the upgrade was successful by checking the GitLab version in the UI or via `gitlab-rake gitlab:env:info`
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in GitLab
Scoped from the published advisory
- Consultation4.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,544.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-39933 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-39933 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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