Arbitrary code execution via prototype property access
Published Nov 14, 2025 · Updated Nov 14, 2025
Prototype pollution in expr-eval 2.0.2 and earlier allows attackers to execute arbitrary code through crafted expressions. In src/evaluate.js, the IVAR evaluation path accepts constructor, prototype, and proto identifiers and resolves inherited properties without blocking prototype-chain access. An embedding application must pass attacker-controlled expressions to the evaluator; successful exploitation executes code with the host process's privileges.
Summary
What happened
Prototype pollution in expr-eval 2.0.2 and earlier allows attackers to execute arbitrary code through crafted expressions. In src/evaluate.js, the IVAR evaluation path accepts constructor, prototype, and proto identifiers and resolves inherited properties without blocking prototype-chain access. An embedding application must pass attacker-controlled expressions to the evaluator; successful exploitation executes code with the host process's privileges.
The record
- CVE
- CVE-2025-13204
- Published
- Nov 14, 2025
- Updated
- Nov 14, 2025
- Vendor
- Matthew Crumley
- Product
- expr-eval
- Classifications
- CWE-1321
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Nov 14, 2025CVE publishedPublication date reported by the CVE source.
- Nov 14, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <=2.0.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- SSTImap expr-eval exploitation pluginfunctional · unverified
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Technologies
Your stack
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Your stack
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