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Fencer Intel
high 7.5

CVE-2017-16086 json

ReDoS via long UserAgent header in ua-parser

published 8y ago modified 4mo ago also GHSA-pmg9-p9r2-6q87 , EUVD-2018-0303

cvss
7.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
9.1%
EPSS 9.1% chance of exploitation in 30 days, percentile 95%
public exploits
1
Metasploit

Summary

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.

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Exploit prediction

9.10% chance of exploitation in the next 30 days, higher than 95% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

CVSS scores

assigned by version score vector
NVD 3.0 7.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected packages

ecosystem package affected fixed in
npm ua-parser
<=0.3.5
no fix listed

Affected products

  • HackerOne ua-parser node module

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.