CVE-2026-54737 @phun-ky/defaults-deep Has a Prototype Pollution issue via Unsafe Recursive Property Merging
Prototype pollution in defaults-deep allows attackers to modify Object.prototype, potentially leading to code execution or privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-54737?
CVE-2026-54737 is a high-severity vulnerability in phun-ky defaults-deep, published on 31 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
@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.
Weakness: CWE-1321
Which versions are affected by CVE-2026-54737?
2 open source packages ship an affected version, including @phun-ky/defaults-deep.
| Package | Affected | Fixed in |
|---|---|---|
@phun-ky/defaults-deep npm | All versions | 2.0.5 |
@phun-ky/defaults-deep npm | All versions | 2.0.5 |
How do I fix CVE-2026-54737?
Upgrade @phun-ky/defaults-deep to 2.0.5 or later.
Is CVE-2026-54737 being exploited?
There is no known exploitation of CVE-2026-54737 in the wild and no public exploit code.
Sources
Also known as GHSA-mj3g-7xcc-x4vh.