CVE-2025-12758

HIGH

Package Validator <13.15.22 - Incomplete Filtering

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 2 public exploits for CVE-2025-12758. PoCs published by open-flaw, dajneem23.

AI-analyzed exploit summary The repository contains a functional PoC demonstrating CVE-2025-12758, a Unicode variation selector bypass in the `validator.js` npm package's `isLength()` function. The PoC shows how strings with variation selectors are incorrectly validated, allowing longer inputs to pass length checks.

Description

Versions of the package validator before 13.15.22 are vulnerable to Incomplete Filtering of One or More Instances of Special Elements in the isLength() function that does not take into account Unicode variation selectors (\uFE0F, \uFE0E) appearing in a sequence which lead to improper string length calculation. This can lead to an application using isLength for input validation accepting strings significantly longer than intended, resulting in issues like data truncation in databases, buffer overflows in other system components, or denial-of-service.

Exploits (2)

github WORKING POC
by open-flaw · javascriptpoc
https://github.com/open-flaw/CVE-2025-12758

The repository contains a functional PoC demonstrating CVE-2025-12758, a Unicode variation selector bypass in the `validator.js` npm package's `isLength()` function. The PoC shows how strings with variation selectors are incorrectly validated, allowing longer inputs to pass length checks.

Classification
Working Poc 100%
Attack Type
Other
Complexity
Trivial
Reliability
Reliable
Target: validator.js npm package < 13.15.22
No auth needed
Prerequisites: Node.js environment · validator.js version < 13.15.22
devstral-2 · analyzed May 16, 2026 Full analysis →
nomisec WORKING POC
by dajneem23 · poc
https://github.com/dajneem23/CVE-2025-12758

This PoC demonstrates a Unicode variation selector bypass in the `validator.js` npm package's `isLength()` function, allowing strings with invisible characters to pass length validation checks. The vulnerability can lead to data truncation, buffer overflows, or DoS attacks.

Classification
Working Poc 100%
Attack Type
Auth Bypass
Complexity
Trivial
Reliability
Reliable
Target: validator.js npm package < 13.15.22
No auth needed
Prerequisites: Node.js environment with vulnerable `validator.js` version installed
devstral-2 · analyzed Feb 16, 2026 Full analysis →

Scores

CVSS v3 7.5
EPSS 0.0044
EPSS Percentile 34.8%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation poc
Automatable yes
Technical Impact partial

Details

CWE
CWE-172 CWE-792
Status published
Products (2)
npm/validator 0 - 13.15.22npm
validator_project/validator < 13.15.22
Published Nov 27, 2025
Tracked Since Feb 18, 2026