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GHSA-28xv-ph75-77wh

LowCVSS 3.7 / 10
Published Jul 14, 2026·Last modified Jul 14, 2026
Affected Components(0)

No affected components available

Description

Impact

The _.merge(target, source) utility exported by @feathersjs/commons recursively merges source into target by iterating Object.keys(source). When source was produced by JSON.parse and contains a __proto__ (or constructor / prototype) key, that key is returned as an own-enumerable property. The recursive merge then resolves target['__proto__'] to Object.prototype and writes the attacker-supplied properties onto it, polluting the prototype for all plain objects in the process for the lifetime of the Node process.

Scope of real-world risk is limited. No first-party Feathers package routes input — trusted or untrusted — through commons._.merge. The @feathersjs/authentication package, which does merge request-influenced data, uses lodash/merge (prototype-pollution-safe since 4.17.12), not this utility. Exploitation therefore requires a downstream plugin or application to pass JSON-parsed, attacker-controlled input directly through the exported _.merge.

Patches

Fixed in @feathersjs/commons@5.0.45. The fix skips __proto__, constructor, and prototype keys during iteration — the standard remediation used by lodash and others.

Workarounds

Avoid passing JSON-parsed untrusted input through commons._.merge. Freezing Object.prototype or validating/sanitizing keys upstream also mitigates.

Credit

Reported responsibly by Andrew Ridings (@ridingsa).

Risk Scores
Base Score
3.7

The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a low impact on the integrity of the data.

Threat Intelligence
3.4

Limited exploitation activity has been observed. Close monitoring and planned remediation are recommended.

EPSS
0.26%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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