CVE-2025-12758 Validator is Vulnerable to Incomplete Filtering of One or More Instances of Special Elements
An attacker can bypass length validation using Unicode variation selectors, causing data truncation or denial of service in applications using the validator library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-12758?
CVE-2025-12758 is a high-severity denial of service vulnerability in org.webjars.npm:validator, published on 27 Nov 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2025-12758?
2 open source packages ship an affected version, including validator. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
validator npm | All versions | 13.15.22 |
validator npm | All versions | 13.15.22 |
Products include Validator Project Validator.
How do I fix CVE-2025-12758?
Upgrade validator to 13.15.22 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-12758 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-12758 exists.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in org.webjars.npm:validator
Sources
Also known as CLSA-2026-1790175492, GHSA-vghf-hv5q-vc2g, MINI-4jcq-2hm2-3gxc, MINI-jv5q-pv59-w2fc, MINI-x33q-f99v-r4xw, ROOT-APP-NPM-CVE-2025-12758.