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Ua ParserApplication · Ua Parser Project

CVE-2017-16086

HIGH · 7.5 CVSS v3.0 Published 2018-06-07
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

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
ua-parser is a port of Browserscope's user agent parser. ua-parser is vulnerable to a ReDoS (Regular Expression Denial of Service) attack when given a specially crafted UserAgent header.

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 · moderate confidence

The ua-parser library is vulnerable to Regular Expression Denial of Service (ReDoS) when processing specially crafted UserAgent strings. The vulnerability exists in the regex patterns used to parse user agent headers, where certain crafted inputs can cause excessive backtracking, leading to CPU exhaustion and service unavailability.

MitigationUpgrade ua-parser to a patched version that addresses the ReDoS vulnerability in the regex parsing logic, and implement request timeout protections at the application layer to mitigate potential exploitation.

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 ParserApplication
Affected:all versions

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
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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. Check if ua-parser is installed
    Run 'npm list ua-parser' or check package.json dependencies for ua-parser entry
    Affected if ua-parser is listed as a dependency
  2. Verify ua-parser version
    Run 'npm list ua-parser' to see the installed version number
    Affected if Any version of ua-parser is installed (all versions are affected)
  3. Confirm User-Agent parsing is in use
    Search codebase for calls to ua-parser functions such as ua-parser, UAParser, or require('ua-parser').uastring()
    Affected if Codebase parses User-Agent strings using ua-parser

If ua-parser is installed and processes User-Agent headers, the environment is affected by this ReDoS vulnerability in all versions.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade ua-parser to a patched version that addresses the ReDoS vulnerability in the regex parsing logic, and implement request timeout protections at the application layer to mitigate potential exploitation.

Fix this in Ua Parser Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,380
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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-2017-16086 in production — separate from our analysis above.

No notes yet

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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