CVE-2025-62494

Quickjs Project Quickjs ≤ 2025-09-13

Public PoC

Published

16 October 2025

Modified

29 October 2025

CVSS Score v4 7.1

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Raw vector

CVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:P/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Score 0.0048 39th percentile

Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2025-62494 is a high-severity Incorrect Type Conversion or Cast (CWE-704) vulnerability in Quickjs Project Quickjs. Its CVSS base score is 7.1 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 39th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-15 (Development Process, Standards, and Tools) — see the control section below for these in your framework.

EU & UK References

🇪🇺 ENISA EUVD: EUVD-2025-34780

Vulnerability Data

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.

CWE(s): CWE-704

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation

Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.

attack.mitre.org →

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1203 Exploitation for Client Execution Execution

Adversaries may exploit software vulnerabilities in client applications to execute code.

attack.mitre.org →

T1210 Exploitation of Remote Services Lateral Movement

Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.

attack.mitre.org →

T1212 Exploitation for Credential Access Credential Access

Adversaries may exploit software vulnerabilities in an attempt to collect credentials.

attack.mitre.org →

T1687 Exploitation for Defense Impairment Defense Impairment

Adversaries may exploit vulnerabilities in security software, infrastructure, or defensive components to degrade, disable, or otherwise continue to impair their ability to prevent, detect, or respond to malicious activity.

attack.mitre.org →

Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-31922Same product: Quickjs Project Quickjs

CVE-2023-48184Same product: Quickjs Project Quickjs

CVE-2025-62491Same product: Quickjs Project Quickjs

CVE-2025-62490Same product: Quickjs Project Quickjs

CVE-2025-62495Same product: Quickjs Project Quickjs

CVE-2025-62492Same product: Quickjs Project Quickjs

CVE-2025-62493Same product: Quickjs Project Quickjs

CVE-2025-62496Same product: Quickjs Project Quickjs

CVE-2025-69653Same product: Quickjs Project Quickjs

CVE-2023-48183Same product: Quickjs Project Quickjs

Affected Assets

quickjs project

quickjs

≤ 2025-09-13

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and evaluation (static analysis, fuzzing, unit tests) directly finds incorrect type conversions or casts.

SA-15 Development Process, Standards, and Tools partial match

Requiring documented development standards and tools can mandate safe typing, casting rules, and compiler checks that stop the weakness from being introduced.

SA-8 Security and Privacy Engineering Principles partial match

Security engineering principles can require type-safe design and casting practices that structurally avoid incorrect conversions.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match

prevents

Secure SDLC practices directly prevent type-conversion flaws via coding standards, reviews, and testing.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match

finds

Security testing can uncover type-conversion defects before release.

A.8.25 Secure development life cycle partial match

prevents

Secure development lifecycle includes type-safety reviews that reduce incorrect casts.

A.8.26 Application security requirements partial match

prevents

Application security requirements can mandate strong typing and safe casting rules.

A.8.27 Secure system architecture and engineering principles partial match

degrades

Secure architecture principles discourage unsafe type conversions in design.