ts-fns has prototype pollution vulnerability

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

6.3 · CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2025-57351: 0.43% estimated exploitation activity in the next 30 days; percentile 37.20 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

24 Sep 2025, 21:30 UTC

Last modified by the source

25 Sep 2025, 17:57 UTC

Source last checked

26 Oct 2026, 12:38 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-g7wq-wggw-vmhg

2. Revision 2 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-g7wq-wggw-vmhg

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# Patch Next advisory brief: CVE-2025-57351

Advisory: ts-fns has prototype pollution vulnerability
IDs: CVE-2025-57351, GHSA-g7wq-wggw-vmhg
Record: https://patchnext.com/advisories/cve-2025-57351 (revision 3, source checked 26 Oct 2026, 12:38 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm ts-fns: affected <= 13.1.3

## Suggested inspection (read-only)
- `npm ls ts-fns --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on ts-fns.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-g7wq-wggw-vmhg (OSV record GHSA-g7wq-wggw-vmhg lists affected ranges: npm ts-fns >=0 <=13.1.3)
- Verified: https://github.com/advisories/GHSA-g7wq-wggw-vmhg (GitHub-reviewed advisory GHSA-g7wq-wggw-vmhg lists affected ranges: npm ts-fns >=0 <=13.1.3)

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