dbcve.org
Ua Parser JsApplication · Ua Parser Js Project

CVE-2026-48125

MEDIUM · 5.3 CVSS v3.1 Published 2026-07-14
Fix available
A fix is available. Upgrade to 2.0.10 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click 5 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
UAParser.js is a JavaScript library to detect browsers, operating systems, CPUs, and devices from user-agent data. From 2.0.1 until 2.0.10, a regular expression denial-of-service vulnerability exists when using the Client Hints API. By sending a crafted Sec-CH-UA-Model header to an application that calls UAParser(headers).withClientHints(), an attacker can cause excessive CPU time due to catastrophic backtracking in the device regex because Client Hints values are copied without the UA_MAX_LENGTH limit used for User-Agent values. This issue is fixed in version 2.0.10.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

UAParser.js versions 2.0.1-2.0.10 contain a ReDoS vulnerability in the device regex when processing Client Hints. Attackers can send a crafted Sec-CH-UA-Model header to trigger catastrophic backtracking because Client Hints values bypass the UA_MAX_LENGTH length limit applied to standard User-Agent strings, causing excessive CPU consumption and potential service denial.

MitigationUpgrade UAParser.js to version 2.0.10 or later. If immediate upgrading is not feasible, consider implementing request rate limiting or input validation on the Sec-CH-UA-Model header to limit header length before passing to UAParser.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Ua Parser JsApplication
Affected:>= 2.0.1, < 2.0.10

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify UAParser.js installation and version
    Check package.json dependencies, run 'npm list uaparser-js' or 'yarn list uaparser-js', or programmatically via 'require("ua-parser-js").VERSION' or 'UAParser()().getUA()' to confirm the library is present and retrieve its version number
    Affected if Version is 2.0.1 through 2.0.10 (inclusive)
  2. Locate the entry point where UAParser.js is initialized
    Search source code for 'UAParser' or 'ua-parser-js' require/import statements to find where the parser is instantiated; check if it's used in request handling middleware
    Affected if The parser is used in any code path that handles incoming HTTP requests
  3. Determine if Client Hints headers are processed
    Search code for references to 'Sec-CH-UA-Model' header or Client Hints processing (often via 'getDevice()' method or similar); inspect network/request handling code to see if the Sec-CH-UA-Model header value is passed to the UAParser device parser
    Affected if Code explicitly or implicitly processes the Sec-CH-UA-Model header through UAParser's device parsing function
  4. Check if input validation limits header length
    Inspect middleware or preprocessing code that handles incoming headers before passing to UAParser; look for any length checks, sanitization, or rate limiting on Sec-CH-UA-Model specifically
    Affected if No length validation or input sanitization is performed on Sec-CH-UA-Model before it reaches UAParser

Environment is affected if UAParser.js version is between 2.0.1-2.0.10 AND the Sec-CH-UA-Model Client Hint header is processed by the parser without prior length validation.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 2.0.10 or later
Fixed in 2.0.10
Interim mitigation

Upgrade UAParser.js to version 2.0.10 or later. If immediate upgrading is not feasible, consider implementing request rate limiting or input validation on the Sec-CH-UA-Model header to limit header length before passing to UAParser.

Recommended fix High confidence

2.0.10

  1. Check current installed version of UAParser.js in the project (e.g., npm list uaparser.js)
  2. Update UAParser.js to version 2.0.10 using the project's package manager (e.g., npm install [email protected] or yarn add [email protected])
  3. Verify the installation was successful and the correct version is now installed
  4. Rebuild and redeploy any applications that use this library

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Ua Parser Js Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing8.0 h
  • Review / QA3.0 h
15.0 hours of engineering $2,500
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,000.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-48125 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-48125 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data