Bug 2491452 (CVE-2026-55388)

Summary: CVE-2026-55388 piscina: piscina: Arbitrary code execution via prototype pollution of filename option
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: abuckta, dkuc, orabin
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in piscina, a Node.js worker pool implementation. This vulnerability allows an attacker to achieve arbitrary code execution by exploiting a prototype pollution issue. By manipulating the `filename` option, an attacker can cause their malicious code to be executed within the worker, potentially compromising the system's confidentiality, integrity, and availability.
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Description OSIDB Bzimport 2026-06-22 18:02:16 UTC 
piscina is a node.js worker pool implementation. Prior to 6.0.0-rc.2, 5.2.0, and 4.9.3, piscina's constructor and run() paths read the filename option via plain member access. Both reads fall through the prototype chain when the caller's options object doesn't have filename as an own property. When Object.prototype.filename is polluted upstream the inherited value flows to worker_threads.Worker import and the attacker's .mjs runs in the worker. This vulnerability is fixed in 6.0.0-rc.2, 5.2.0, and 4.9.3.