Code execution via inherited worker filename
Published Jun 22, 2026 · Updated Jun 22, 2026
Code injection in Piscina before 4.9.3, 5.0.0-alpha.0 through 5.1.4, and 6.0.0-rc.1 allows remote attackers to run worker code. The constructor and run() read options.filename through the prototype chain, so a polluted Object.prototype.filename reaches worker_threads.Worker as an attacker-controlled module path. Exploitation requires an upstream prototype-pollution source, a readable attacker-controlled .mjs file, and caller-supplied options without an own filename property; the module executes with the Node.js process authority.
Summary
What happened
Code injection in Piscina before 4.9.3, 5.0.0-alpha.0 through 5.1.4, and 6.0.0-rc.1 allows remote attackers to run worker code. The constructor and run() read options.filename through the prototype chain, so a polluted Object.prototype.filename reaches worker_threads.Worker as an attacker-controlled module path. Exploitation requires an upstream prototype-pollution source, a readable attacker-controlled .mjs file, and caller-supplied options without an own filename property; the module executes with the Node.js process authority.
The record
- CVE
- CVE-2026-55388
- Published
- Jun 22, 2026
- Updated
- Jun 22, 2026
- Vendor
- Piscina
- Product
- Piscina
- Classifications
- CWE-1321, CWE-94, T1059.007
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 22, 2026CVE publishedPublication date reported by the CVE source.
- Jun 22, 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=< 4.9.3
- Affected versionversion=>= 5.0.0-alpha.0, < 5.2.0
- Affected versionversion=>= 6.0.0-rc.1, < 6.0.0-rc.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
- Piscina inherited filename proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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