What’s Vulnerable › Vulnerabilities

CVE-2026-55388: piscina: Prototype Pollution Gadget → RCE via inherited options.filename

• Severity: high (CVSS 8.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-22 · updated 2026-10-25
• Weakness: CWE-94

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.

Affected products

• piscinajs piscina: before 4.9.3; from 5.0.0-alpha.0, < 5.2.0; from 6.0.0-rc.1, < 6.0.0-rc.2

References

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

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