Use After Free Vulnerability in QuickJS by QuickJS-ng
CVE-2026-3979

4.8MEDIUM

Key Information:

Vendor

Quickjs-ng

Status
Quickjs
Vendor
CVE Published:
12 March 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-3979?

A vulnerability in QuickJS-ng affecting versions up to 0.12.1 has been identified, wherein the js_iterator_concat_return function may lead to a use after free scenario. This flaw necessitates local access for exploitation and poses a risk of unauthorized access or manipulation of processes. A patch addressing this issue has been developed and made available, which users are encouraged to apply to mitigate potential exploits.

Affected Version(s)

quickjs 0.12.0

quickjs 0.12.1

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-3979 - Proof of Concept

References

https://vuldb.com/?id.350414
vdb-entrytechnical-description
https://vuldb.com/?ctiid.350414
signaturepermissions-required
https://vuldb.com/?submit.769600
third-party-advisory

CVSS V4

Score:
4.8
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
Low
Availability:
Low
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

im-razvan (VulDB User)
.