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TI-2025-38736 Aliases CVE-2025-62494GHSA-7gcv-76g2-94qm

Type confusion in string addition in QuickJS

Priority HIGH 66CWE-704Published · Updated

Key facts

Attack vector
Adjacent network
Privileges required
Low
User interaction
Passive
Attack complexity
High
Attack requirements
Present
Impact type
Code execution
Confidentiality · integrity · availability
High · High · Low
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-704 and the CVSS impact.

Summary

A type confusion vulnerability exists in the handling of the string addition (+) operation within the QuickJS engine. * The code first checks if the left-hand operand is a string. * It then attempts to convert the right-hand operand to a primitive value using JS_ToPrimitiveFree. This conversion can trigger a callback (e.g., toString or valueOf). * During this callback, an attacker can modify the type of the left-hand operand in memory, changing it from a string to a different type (e.g., an object or an array). * The code then proceeds to call JS_ConcatStringInPlace, which still treats the modified left-hand value as a string. This mismatch between the assumed type (string) and the actual type allows an attacker to control the data structure being processed by the concatenation logic, resulting in a type confusion condition. This can lead to out-of-bounds memory access, potentially resulting in memory corruption and arbitrary code execution in the context of the QuickJS runtime.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00526 44th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed QuickJS (QuickJS): 2025-09-13

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
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
QuickJSQuickJS2025-04-26 to before 2025-09-132025-09-13Patch availableCNA
  • QuickJS VendorQuickJS Affected 2025-04-26 to before 2025-09-13 Fixed in 2025-09-13 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:quickjs_project:quickjs:*:*:*:*:*:*:*:*before 2025-09-13VulnerableQuickJS
  • cpe:2.3:a:quickjs_project:quickjs:*:*:*:*:*:*:*:* Versions before 2025-09-13 Vulnerable ·QuickJS

Remediation

  • Fix · CNA QuickJS (QuickJS) Fixed in 2025-09-13

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    QuickJS 2025-09-13

    7 records Highest priority Priority HIGH 4 HIGH, 3 MEDIUM

    Other records, highest priority first

    • TI-2025-38733 Use-after-free in js_std_promise_rejection_check in QuickJSPriority HIGH 73
    • TI-2025-38738 Integer overflow in js_bigint_from_string in QuickJSPriority HIGH 66
    • TI-2025-38737 Type confusion in string addition in QuickJSPriority HIGH 66
    Show all 7 records →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2025-62494
  2. 2026-10-03 Alias added: GHSA-7gcv-76g2-94qm

References

Exploit 1

Other 1

  • TI-2025-38733 Use-after-free in js_std_promise_rejection_check in QuickJS CVSS 4.0HIGH 8.8
  • TI-2025-42911 A crafted JavaScript input executed with the QuickJS release 2025-09-13, fixed in commit… CVSS 3.1HIGH 7.5
  • TI-2025-29366 quickjs-ng through 0.9.0 has an incorrect size calculation in JS_ReadBigInt for a BigInt… CVSS 3.1HIGH 8.4
  • TI-2025-38738 Integer overflow in js_bigint_from_string in QuickJS CVSS 4.0HIGH 7.1
  • TI-2025-38737 Type confusion in string addition in QuickJS CVSS 4.0HIGH 7.1
  • TI-2023-15270 QuickJS commit 2788d71 was discovered to contain a stack-overflow via the component js_proxy_isArray at quickjs.c. CVSS 3.1HIGH 7.5
See all 13 →

Sources

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