Prototype pollution via writable regex guard
Published Mar 27, 2026 · Updated Mar 27, 2026
Prototype pollution in Locutus 2.0.39 through 3.0.24 allows attackers to modify Object.prototype through crafted parse_str input. The function relies on writable RegExp.prototype.test to reject dangerous keys, so a prior gadget can override the method and disable the guard before segment assignment. Exploitation requires an earlier prototype-pollution gadget in the same process and can corrupt properties inherited by application objects.
Summary
What happened
Prototype pollution in Locutus 2.0.39 through 3.0.24 allows attackers to modify Object.prototype through crafted parse_str input. The function relies on writable RegExp.prototype.test to reject dangerous keys, so a prior gadget can override the method and disable the guard before segment assignment. Exploitation requires an earlier prototype-pollution gadget in the same process and can corrupt properties inherited by application objects.
The record
- CVE
- CVE-2026-33994
- Published
- Mar 27, 2026
- Updated
- Mar 27, 2026
- Vendor
- Locutus
- Product
- Locutus
- Classifications
- CWE-1321
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 27, 2026CVE publishedPublication date reported by the CVE source.
- Mar 27, 2026Record 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=>= 2.0.39, < 3.0.25
What conditions does exploitation require?
What is affected?
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
- GHSA-vc8f-x9pp-wf5p parse_str reproductionproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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