ts-fns has prototype pollution vulnerability

published 2025-09-24 13 mo ago modified 2026-06-17 4 mo ago also GHSA-g7wq-wggw-vmhg , EUVD-2025-31070

cvss: 6.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits: 0; none known

A prototype pollution vulnerability exists in the ts-fns package versions prior to 13.0.7, where insufficient validation of user-provided keys in the assign function allows attackers to manipulate the Object.prototype chain. By leveraging this flaw, adversaries may inject arbitrary properties into the global object's prototype, potentially leading to application crashes, unexpected code execution behaviors, or bypasses of security-critical validation logic dependent on prototype integrity. The vulnerability stems from improper handling of deep property assignment operations within the library's public API functions. This issue remains unaddressed in the latest available version.

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 13 mo ago (2025-09-25)

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
CNA	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

Affected packages

ecosystem	package	affected	fixed in
npm	ts-fns	<=13.1.3	no fix listed

Classification

Weakness

CWE-1321 Improperly Controlled Modification of Object Prototype Attributes

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary