CVE-2026-3979Public exploit

Heap corruption via re-entrant iterator double release

Published Mar 12, 2026 · Updated Mar 12, 2026

Use-after-free in QuickJS-NG QuickJS 0.12.0 through 0.12.1 allows local users to corrupt heap memory via crafted JavaScript. Within js_iterator_concat_next, user-controlled @@iterator code can re-enter return() before the running guard is set, freeing values that execution later releases again. Low-privileged local code execution is required; the demonstrated consequence is a heap-use-after-free and process abort, while broader code-execution impact is unproven.

CVSS severity5.3
Medium
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in QuickJS-NG QuickJS 0.12.0 through 0.12.1 allows local users to corrupt heap memory via crafted JavaScript. Within js_iterator_concat_next, user-controlled @@iterator code can re-enter return() before the running guard is set, freeing values that execution later releases again. Low-privileged local code execution is required; the demonstrated consequence is a heap-use-after-free and process abort, while broader code-execution impact is unproven.

The record

CVE
CVE-2026-3979
Published
Mar 12, 2026
Updated
Mar 12, 2026
Vendor
QuickJS-NG
Product
QuickJS
Classifications
CWE-119, CWE-416, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 12, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 12, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.12.0
  2. Affected versionversion=0.12.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

QuickJS-NG · QuickJSversion=0.12.0; version=0.12.1

Published CVSS scores

4.3VulDBAV:L/AC:L/Au:S/C:P/I:P/A:P
5.3VulDBCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
1.9VulDBCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-416Use After Free
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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