Cyber Resilience

CVE-2025-62495

Memory Safety in Quickjs Project Quickjs ≤ 2025-09-13

Public PoCMemory Safety
Published
16 October 2025
Modified
29 October 2025
CVSS Score v4 7.1
Click a component to see what it means
Raw vectorCVSS: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 0.0043 35th percentile
Risk Priority 55 floored blend · peak EPSS

Summary

CVE-2025-62495 is a high-severity Wrap or Wraparound (CWE-191) 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 35th 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-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

An integer overflow vulnerability exists in the QuickJS regular expression engine (libregexp) due to an inconsistent representation of the bytecode buffer size. * The regular expression bytecode is stored in a DynBuf structure, which correctly uses a $\text{size}\_\text{t}$ (an unsigned…

more

type, typically 64-bit) for its size member. * However, several functions, such as re_emit_op_u32 and other internal parsing routines, incorrectly cast or store this DynBuf $\text{size}\_\text{t}$ value into a signed int (typically 32-bit). * When a large or complex regular expression (such as those generated by a recursive pattern in a Proof-of-Concept) causes the bytecode size to exceed $2^{31}$ bytes (the maximum positive value for a signed 32-bit integer), the size value wraps around, resulting in a negative integer when stored in the int variable (Integer Overflow). * This negative value is subsequently used in offset calculations. For example, within functions like re_parse_disjunction, the negative size is used to compute an offset (pos) for patching a jump instruction. * This negative offset is then incorrectly added to the buffer pointer (s->byte\_code.buf + pos), leading to an out-of-bounds write on the first line of the snippet below: put_u32(s->byte_code.buf + pos, len);

CWE(s)

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.
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.
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-62490Same product: Quickjs Project Quickjs
CVE-2023-48184Same product: Quickjs Project Quickjs
CVE-2025-62491Same product: Quickjs Project Quickjs
CVE-2025-62493Same product: Quickjs Project Quickjs
CVE-2025-62492Same product: Quickjs Project Quickjs
CVE-2025-62494Same product: Quickjs Project Quickjs
CVE-2025-62496Same product: Quickjs Project Quickjs
CVE-2023-31922Same product: Quickjs Project Quickjs
CVE-2025-69654Same 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

Developer testing and static/dynamic analysis directly find integer underflow defects before code is released.

Security engineering principles require use of safe arithmetic constructs or language features that structurally eliminate integer underflow during subtraction.

Input validation can reject or sanitize values that would cause a subtraction to underflow the representable range.

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 full match
prevents

Secure SDLC practices directly prevent integer underflow defects via input validation, bounds checking, and static analysis.

ID.RA-01 partial match
prevents

Vulnerability scanning and code analysis can surface underflow flaws after they are introduced.

PR.PS-02 partial match
prevents

Routine patching can remediate known underflow bugs once they are discovered in deployed software.

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.

finds

Security testing in development catches integer underflow defects before release.

prevents

Secure development lifecycle mandates input validation and arithmetic checks that prevent integer underflow.

prevents

Application security requirements include bounds checking and safe arithmetic to avoid underflow conditions.

prevents

Secure architecture principles require defensive coding patterns that mitigate integer wraparound risks.

prevents

Secure coding standards directly prescribe safe integer handling and overflow/underflow prevention.

References