CVE-2025-12758Public exploitNetwork attack vector

Input-validation bypass via variation-selector miscounting

Published Nov 27, 2025 · Updated Aug 8, 2026

Input-validation bypass in validator.js before 13.15.22 allows attackers to submit strings longer than an isLength limit. isLength subtracts every U+FE0E or U+FE0F variation selector from the measured length instead of discounting one only when it follows a base character. Exploitation requires a consuming application to rely on isLength for a maximum; accepted excess input can cause data truncation or a service interrupt in downstream handling.

CVSS severity8.7
High
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Input-validation bypass in validator.js before 13.15.22 allows attackers to submit strings longer than an isLength limit. isLength subtracts every U+FE0E or U+FE0F variation selector from the measured length instead of discounting one only when it follows a base character. Exploitation requires a consuming application to rely on isLength for a maximum; accepted excess input can cause data truncation or a service interrupt in downstream handling.

The record

CVE
CVE-2025-12758
Published
Nov 27, 2025
Updated
Aug 8, 2026
Vendor
validatorjs
Product
validator.js
Classifications
CWE-172, CWE-792, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 27, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <13.15.22

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

validatorjs · validator.jsversion=0 <13.15.22

Published CVSS scores

7.7SnykCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P
8.7SnykCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
7.5SnykCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-172Encoding Error
CWE-792Incomplete Filtering of One or More Instances of Special Elements
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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