CVE-2023-2142
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 · uneditedIn Nunjucks versions prior to version 3.2.4, it was possible to bypass the restrictions which are provided by the autoescape functionality. If there are two user-controlled parameters on the same line used in the views, it was possible to inject cross site scripting payloads using the backslash \ character.
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 confidenceNunjucks versions before 3.2.4 contain an autoescape bypass vulnerability where the backslash character can be used to inject XSS payloads when two user-controlled parameters exist on the same line in templates. This allows attackers to circumvent the autoescape protection intended to neutralize malicious input.
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< 3.2.4CVSS 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
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
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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Identify Nunjucks installation path and versionRun 'npm list nunjucks' or check package.json dependencies to see the installed version of NunjucksAffected if The installed version is below 3.2.4 (e.g., 3.2.3, 3.2.2, 3.0.x, etc.)
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Locate Nunjucks template filesSearch for .njk or .html template files in your project that are rendered using NunjucksAffected if Templates exist and are used to render user-provided data
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Check if autoescape is enabled in your Nunjucks environmentInspect your Nunjucks environment configuration code for 'autoescape: true' setting in the Environment or Loader configurationAffected if Autoescape is enabled but templates contain multiple user inputs on the same line
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Audit templates for multiple user inputs on single linesReview template files and search for patterns where two or more variables (e.g., {{ userInput1 }}{{ userInput2 }} or {{ userInput }} followed by {{ anotherInput }}) appear adjacent or on the same line without intervening static textAffected if Templates contain two or more user-controlled variables rendered on the same line
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Search for backslash characters near user input renderingSearch template files for backslash characters (\) appearing before or between user input variables, particularly patterns like {{ \ }}{{ userInput }} or similar escape sequencesAffected if Backslash characters are present in templates that also render user input on the same line
You are affected if Nunjucks version is below 3.2.4 AND your templates render multiple user inputs on the same line while autoescape is enabled, allowing backslash characters to bypass the autoescape protection.
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 · scoped3.2.4
Upgrade Nunjucks to version 3.2.4 or later to patch the autoescape bypass. Review existing templates for instances where multiple user inputs appear on the same line and ensure they are properly escaped.
Nunjucks 3.2.4 or later
- Check the current installed version of Nunjucks in your project by running: npm list nunjucks or pip show nunjucks (depending on your package manager)
- Upgrade Nunjucks to version 3.2.4 or later. For npm: run npm install nunjucks@^3.2.4 or npm update nunjucks
- For pip: run pip install --upgrade nunjucks>=3.2.4
- After upgrading, verify the new version is installed: npm list nunjucks or pip show nunjucks
- Test your application to confirm the autoescape functionality works correctly and the XSS vulnerability is mitigated
- If using a package-lock.json or pip lock file, regenerate it to lock the fixed version
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-2142 — 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-2023-2142 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
- No spam, self-promotion, credentials, or personal data