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TI-2026-26334 Aliases CVE-2026-33994GHSA-vc8f-x9pp-wf5p

Locutus Prototype Pollution due to incomplete fix for CVE-2026-25521

Priority HIGH 69CWE-1321Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
Present
Impact type
—
Confidentiality · integrity · availability
None · Low · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.

Summary

Locutus brings stdlibs of other programming languages to JavaScript for educational purposes. Starting in version 2.0.39 and prior to version 3.0.25, a prototype pollution vulnerability exists in the `parse_str` function of the npm package locutus. An attacker can pollute `Object.prototype` by overriding `RegExp.prototype.test` and then passing a crafted query string to `parse_str`, bypassing the prototype pollution guard. This vulnerability stems from an incomplete fix for CVE-2026-25521. The CVE-2026-25521 patch replaced the `String.prototype.includes()`-based guard with a `RegExp.prototype.test()`-based guard. However, `RegExp.prototype.test` is itself a writable prototype method that can be overridden, making the new guard bypassable in the same way as the original — trading one hijackable built-in for another. Version 3.0.25 contains an updated fix.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00568 47th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed locutus (locutusjs): 3.0.25locutus (npm): 3.0.25

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
locutusjslocutus2.0.39 to before 3.0.253.0.25Patch availableCNA
—locutus (npm)2.0.39 to before 3.0.253.0.25Patch availableGHSA-vc8f-x9pp-wf5p
  • locutus Vendorlocutusjs Affected 2.0.39 to before 3.0.25 Fixed in 3.0.25 Patch available CNA
  • locutus (npm) Vendor— Affected 2.0.39 to before 3.0.25 Fixed in 3.0.25 Patch available GHSA-vc8f-x9pp-wf5p

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:locutus:locutus:*:*:*:*:*:node.js:*:*2.0.39 to before 3.0.25Vulnerablelocutusjs
  • cpe:2.3:a:locutus:locutus:*:*:*:*:*:node.js:*:* Versions 2.0.39 to before 3.0.25 Vulnerable ·locutusjs

Remediation

  • Fix · CNA locutus (locutusjs) Fixed in 3.0.25
  • Fix · GHSA-vc8f-x9pp-wf5p locutus (npm) Fixed in 3.0.25 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Not affected: 1 product
  • Logging Subsystem for Red Hat OpenShift

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-33994
  2. 2026-10-03 Alias added: GHSA-vc8f-x9pp-wf5p
  3. 2026-10-25 EPSS moved to the below the 50th percentile

References

Exploit 1

Patch 1

Advisory 1

Other 4

  • TI-2026-24833 Locutus: RCE via unsanitized input in create_function() CVSS 3.1CRITICAL 9.8
  • TI-2026-26333 Locutus has Prototype Pollution via __proto__ Key Injection in unserialize() CVSS 4.0MEDIUM 6.9
  • TI-2026-23234 Locutus: Remote Code Execution (RCE) in locutus call_user_func_array due to Code Injection CVSS 3.1HIGH 8.1
  • TI-2020-06239 Prototype pollution in locutus CVSS 3.1CRITICAL 9.8
  • TI-2026-20630 Locutus is vulnerable to Prototype Pollution CVSS 4.0CRITICAL 9.4
  • TI-2021-06085 Regular expression denial of service (ReDoS) in locutus CVSS 3.1HIGH 7.5

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences