CVE-2026-55388

piscina: Prototype Pollution Gadget → RCE via inherited options.filename

State: Published
Severity: 8.1 High
Published: Jun 22, 2026
Updated: Jun 23, 2026
Reserved: Jun 16, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	8.1 High	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H	GitHub_M

Weaknesses

CWE-94 Improper Control of Generation of Code ('Code Injection')
CWE-1321 Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

Affected Products

Product	Versions
piscinapiscinajs	< 4.9.3Affected >= 5.0.0-alpha.0, < 5.2.0Affected >= 6.0.0-rc.1, < 6.0.0-rc.2Affected

References

https://github.com/piscinajs/piscina/security/advisories/GHSA-x9g3-xrwr-cwfg

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