CVE-2017-16086: ua-parser is a port of Browserscope's user agent parser

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HIGH 7.5REMOTEMITIGATE

CVE-2017-16086 is a high-severity flaw (CVSS 7.5) affecting ua-parser. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
EPSS top 5%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	9.1% (top 5%)
CISA exploited list	No
Weakness	CWE-400
Published	2018-06-07
Last modified	2026-06-17

Publisher (CNA): HackerOne · Vendor: ua-parser project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2018-06-07 02:29 UTCPublished CVE record published
2026-06-17 01:08 UTCUpdated Record last modified

ua-parser project ua-parser MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

npm ls ua-parser

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Metasploit: ua-parser-js npm module ReDoS

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2017-16086?

ua-parser: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-16086 being exploited?

CVE-2017-16086 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2017-16086 affect?

CVE-2017-16086 affects ua-parser. Severity is high (CVSS 7.5). 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.

How urgent is CVE-2017-16086?

Priority 60/100. High severity; EPSS top 5%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

References

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