@phun-ky/defaults-deep Has a Prototype Pollution issue via Unsafe Recursive Property Merging

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

@phun-ky/defaults-deep is a library like lodash defaultsDeep with array preservation and no lodash dependency. Prior to 2.0.5, defaultsDeep() recursively merges user-supplied objects without filtering proto, constructor, and prototype, allowing properties to be written to Object.prototype. This issue is fixed in version 2.0.5.

Source published

31 Jul 2026 17:48:42 UTC

Source modified

31 Jul 2026 19:00:41 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

@phun-ky/defaults-deep is a library like lodash defaultsDeep with array preservation and no lodash dependency. Prior to 2.0.5, defaultsDeep() recursively merges user-supplied objects without filtering proto, constructor, and prototype, allowing properties to be written to Object.prototype. This issue is fixed in version 2.0.5.

Source published

31 Jul 2026 18:17:17 UTC

Source modified

23 Oct 2026 23:10:00 UTC

Observed here

25 Oct 2026 13:17:34 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 7.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

### Impact A prototype pollution vulnerability exists in @phun-ky/defaults-deep prior to version 2.0.5. The library recursively merged user-supplied objects without filtering unsafe property names such as `__proto__`, `constructor`, and `prototype`. An attacker able to supply crafted input could cause properties to be written to `Object.prototype`, resulting in prototype pollution affecting all objects within the running process. Applications that pass untrusted input to `defaultsDeep()` may be impacted. Depending on how the application uses merged objects, this could lead to unexpected behavior, logic bypasses, denial of service, or other security issues. ### Patches This issue has been fixed in version 2.0.5. Users should upgrade to version 2.0.5 or later. The fix prevents unsafe prototype-related keys (`__proto__`, `constructor`, and `prototype`) from being processed during recursive merge operations and includes regression tests covering known prototype pollution vectors. ### Workarounds Users unable to upgrade should ensure that untrusted input is sanitized before being passed to `defaultsDeep()`. At a minimum, applications should reject or remove the following property names from all levels of user-controlled objects: - `__proto__` - `constructor` - `prototype` Upgrading to a patched version remains the recommended mitigation.

Source published

31 Jul 2026 17:49:08 UTC

Source modified

31 Jul 2026 18:11:48 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Publisher rating · HIGH