SecuriTricks - CVE-2025-62496

Description

A vulnerability exists in the QuickJS engine's BigInt string parsing logic (js_bigint_from_string) when attempting to create a BigInt from a string with an excessively large number of digits. The function calculates the necessary number of bits (n_bits) required to store the BigInt using the formula: $$\text{n\_bits} = (\text{n\_digits} \times 27 + 7) / 8 \quad (\text{for radix 10})$$ * For large input strings (e.g., $79,536,432$ digits or more for base 10), the intermediate calculation $(\text{n\_digits} \times 27 + 7)$ exceeds the maximum value of a standard signed 32-bit integer, resulting in an Integer Overflow. * The resulting n_bits value becomes unexpectedly small or even negative due to this wrap-around. * This flawed n_bits is then used to compute n_limbs, the number of memory "limbs" needed for the BigInt object. Since n_bits is too small, the calculated n_limbs is also significantly underestimated. * The function proceeds to allocate a JSBigInt object using this underestimated n_limbs. * When the function later attempts to write the actual BigInt data into the allocated object, the small buffer size is quickly exceeded, leading to a Heap Out-of-Bounds Write as data is written past the end of the allocated r->tab array.

Product(s) Impacted

Vendor	Product	Versions
Quickjs	Quickjs	*

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-190

Integer Overflow or Wraparound

The product performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control.

*CPE(s)

Affected systems and software identified for this CVE.

Type	Vendor	Product	Version	Update	Edition	Language	Software Edition	Target Software	Target Hardware	Other Information
a	quickjs	quickjs	/	/	/	/	/	/	/	/

References

https://bellard.org/quickjs/Changelog

https://issuetracker.google.com/434193016

CVSS Score

7.1 / 10

CVSS Data - 4.0

Attack Vector: ADJACENT
Attack Complexity: HIGH
Attack Requirements: PRESENT
Privileges Required: LOW
User Interaction: PASSIVE
Scope:
Confidentiality Impact: HIGH
Integrity Impact: HIGH
Availability Impact: LOW
Exploit Maturity: NOT_DEFINED

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

View Vector String

Timeline

Published: Oct. 16, 2025, 4:15 p.m.
Last Modified: Oct. 16, 2025, 4:15 p.m.

Status : Received

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

cve-coordination@google.com

CVE-2025-62496