CVE-2026-55388
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.
CVSS
- Version: 3.1
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- Base score: 8.1
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days: 0.45%
- Percentile among all scored CVEs: 37
- Score date: 9/30/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
Affected technologies (1)
⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.
CWEs
- CWE-94, CWE-1321
References
Raw JSON (NVD)
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{
"id": "CVE-2026-55388",
"cveTags": [],
"metrics": {
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-55388",
"role": "CISA Coordinator",
"options": [
{
"exploitation": "poc"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"version": "2.0.3",
"timestamp": "2026-06-23T15:50:15.219533Z"
}
}
],
"cvssMetricV31": [
{
"type": "Secondary",
"source": "security-advisories@github.com",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 8.1,
"attackVector": "NETWORK",
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"integrityImpact": "HIGH",
"userInteraction": "NONE",
"attackComplexity": "HIGH",
"availabilityImpact": "HIGH",
"privilegesRequired": "NONE",
"confidentialityImpact": "HIGH"
},
"impactScore": 5.9,
"exploitabilityScore": 2.2
}
]
},
"affected": [
{
"source": "security-advisories@github.com",
"affectedData": [
{
"vendor": "piscinajs",
"product": "piscina",
"versions": [
{
"status": "affected",
"version": "< 4.9.3"
},
{
"status": "affected",
"version": ">= 5.0.0-alpha.0, < 5.2.0"
},
{
"status": "affected",
"version": ">= 6.0.0-rc.1, < 6.0.0-rc.2"
}
]
}
]
}
],
"published": "2026-06-22T18:16:47.930",
"references": [
{
"url": "https://github.com/piscinajs/piscina/security/advisories/GHSA-x9g3-xrwr-cwfg",
"source": "security-advisories@github.com"
},
{
"url": "https://github.com/piscinajs/piscina/security/advisories/GHSA-x9g3-xrwr-cwfg",
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
}
],
"vulnStatus": "Deferred",
"weaknesses": [
{
"type": "Secondary",
"source": "security-advisories@github.com",
"description": [
{
"lang": "en",
"value": "CWE-94"
},
{
"lang": "en",
"value": "CWE-1321"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "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."
}
],
"lastModified": "2026-06-23T17:17:08.180",
"sourceIdentifier": "security-advisories@github.com"
}