Property injection via unsafe __proto__ deserialization
Published Mar 27, 2026 · Updated Mar 27, 2026
Prototype pollution in Locutus before 3.0.25 allows attackers to inject properties into deserialized objects via PHP payloads. expectArrayItems() and expectObject() assign attacker-controlled keys to plain objects with bracket notation, so proto invokes JavaScript's prototype setter instead of creating an own property. Reachability requires consuming code to pass attacker-controlled serialized data to unserialize(); injected properties can alter authorization checks or trigger a TypeError when built-in methods are called.
Summary
What happened
Prototype pollution in Locutus before 3.0.25 allows attackers to inject properties into deserialized objects via PHP payloads. expectArrayItems() and expectObject() assign attacker-controlled keys to plain objects with bracket notation, so proto invokes JavaScript's prototype setter instead of creating an own property. Reachability requires consuming code to pass attacker-controlled serialized data to unserialize(); injected properties can alter authorization checks or trigger a TypeError when built-in methods are called.
The record
- CVE
- CVE-2026-33993
- 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=< 3.0.25
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
- GitHub advisory unserialize proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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