Prototype Pollution in underscore.deep

published 2022-06-28 4 y ago modified 2026-06-17 4 mo ago also EUVD-2022-52749

cvss: 8.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 1.1%; EPSS 1.1% chance of exploitation in 30 days, percentile 64%
public exploits: 0; none known

Underscore.deep is a collection of Underscore mixins that operate on nested objects. Versions of `underscore.deep` prior to version 0.5.3 are vulnerable to a prototype pollution vulnerability. An attacker can craft a malicious payload and pass it to `deepFromFlat`, which would pollute any future Objects created. Any users that have `deepFromFlat` or `deepPick` (due to its dependency on `deepFromFlat`) in their code should upgrade to version 0.5.3 as soon as possible. Users unable to upgrade may mitigate this issue by modifying `deepFromFlat` to prevent specific keywords which will prevent this from happening.

Patch / fix

fixed in 1 links 2

clever underscore.deep 0.5.3

CISA SSVC

Exploitation: Proof of concept is public
Automatable: yes
Technical impact: partial
Assessed: 18 mo ago (2025-04-22)

Exploit prediction

1.05% chance of exploitation in the next 30 days, higher than 64% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/Clever/underscore.deep/security/advisories/GHSA-8j79-hfj5-f2xm referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L
NVD	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	7.5	AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

Clever underscore.deep

Classification

Weakness

CWE-915 Improperly Controlled Modification of Dynamically-Determined Object Attributes
CWE-1321 Improperly Controlled Modification of Object Prototype Attributes

References

github.com /Clever/underscore.deep/commit/b5e109ad05b48371be225fa4d490dd08a94e8ef7
patch, third-party-advisory
github.com /Clever/underscore.deep/security/advisories/GHSA-8j79-hfj5-f2xm
exploit, issue-tracking, patch, third-party-advisory

Sources

CVE List CVE-2022-31106
NVD CVE-2022-31106

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