CVE-2025-12735 is a critical-severity (CVSS 9.8) Code Injection vulnerability in expr-eval. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for expr-eval — see the affected versions and patch details below.
CVE-2025-12735
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-12735.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
expr-evalnpmexpr-eval-forknpmDescription
The 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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | expr-eval | all versions | No fix |
| 📦npm | expr-eval-fork | all versions | 3.0.1npm install expr-eval-fork@3.0.1 |
Affected Products
javascript expression evaluatorjorenbroekemajavascript expression evaluatorsilentmattResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for expr-eval, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
A fix is available for CVE-2025-12735; check the affected-versions list above or the advisory for the patched release of expr-eval, then make sure no transitive dependency still pins the vulnerable range.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.
Frequently Asked Questions
Is CVE-2025-12735 in your dependencies?
Find it across npm, including transitive dependencies.