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VulnerabilityPublished Updated

CVE-2026-55388: piscinajs piscina · Code Injection

Affects piscinajs piscinaSource CVE Database V5

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Not known to be exploited · CVSS 8.1 High · fixed in 6.0.0-rc.2 : patch piscinajs piscina soon.

Data as of 5 Nov 2026, 11:40 UTC

CVSS 3.1 base score
8.1High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (GitHub_M)CVSS 3.18.1
EPSS
0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 6.0.0-rc.2, 5.2.0, 4.9.3
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 22 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

What to do

Upgrade piscina to 6.0.0-rc.2, 5.2.0 or 4.9.3; piscina to 5.2.0 or 4.9.3.

Affected software

ProductAffectedFixed in
piscinajspiscinaAffected
  • >=6.0.0-rc.1 <6.0.0-rc.2
Fixed in
  • 6.0.0-rc.2
piscinajspiscinaAffected
  • >=5.0.0-alpha.0 <5.2.0
Fixed in
  • 5.2.0
piscinajspiscinaAffected
  • <4.9.3
Fixed in
  • 4.9.3
npmpiscinapkg:npm/piscinaOther threatsAffected
  • <4.9.3
  • >=4.9.3 <5.2.0
Fixed in
  • 4.9.3
  • 5.2.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in piscina versions 4.9.3, 5.2.0, and 6.0.0-rc.2. Users should upgrade to at least version 5.2.0 or 4.9.3 to remediate this vulnerability. Patch status is confirmed by the version information in the advisory. No other vendor advisory content is provided.

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.

References

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