CVE-2025-12735
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 · uneditedThe expr-eval library is a JavaScript expression parser and evaluator designed to safely evaluate mathematical expressions with user-defined variables. However, due to insufficient input validation, an attacker can pass a crafted context object or use MEMBER of the context object into the evaluate() function and trigger arbitrary code execution.
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 · moderate confidenceThe expr-eval library fails to properly validate context objects passed to its evaluate() function, allowing attackers to inject or access members of context objects in a way that enables arbitrary code execution. This is a critical RCE vulnerability in a widely-used JavaScript expression parser.
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= 3.0.0<= 2.0.2CVSS 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
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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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Identify installed expr-eval versionRun 'npm ls expr-eval' or check your package.json dependencies for the expr-eval package versionAffected if Version equals 3.0.0 (Jorenbroekema fork) or is 2.0.2 or lower (Silentmatt version)
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Determine which fork is in useInspect the package.json 'name' field in node_modules/expr-eval/package.json or check the main entry point sourceAffected if Package name is 'javascript-expression-evaluator' at version 3.0.0, or 'expr-eval' at version 2.0.2 or below
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Find evaluate() calls with context parametersSearch codebase for pattern: evaluate( and review calls passing a second argument (context object), e.g., expression.evaluate(context)Affected if Code passes a context object as the second argument to evaluate()
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Audit context object for user-controlled dataReview all evaluate() calls identified in step 3 and trace whether any context object properties contain request parameters, body data, or other untrusted inputAffected if Context object contains any data derived from user input, APIs, or external sources without sanitization
Your environment is affected if expr-eval version is 3.0.0 or <=2.0.2 AND your code passes untrusted/user-controlled data as the context object to evaluate() without sanitization.
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 · scopedUpgrade expr-eval to the latest patched version and audit all evaluate() calls to ensure untrusted user input is never passed directly as context objects without sanitization.
expr-eval version 3.0.1 or later (or the equivalent patched version in the 2.x series if staying on major version 2)
- Run `npm list expr-eval` to verify the currently installed version of the expr-eval package
- Run `npm install expr-eval@latest` or `npm install [email protected]` to upgrade to the patched version
- Verify the upgrade was successful by running `npm list expr-eval`
- Review your codebase for any usages of the evaluate() function that accept user-controlled context objects and ensure proper input validation is applied even after upgrading
- Run your application's test suite to confirm the upgrade does not break existing functionality
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-12735 — 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-2025-12735 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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