GHSA-pcqq-5962-hvcw: User agent parser Denial of Service Vulnerability

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Advisory Summary

GHSA-pcqq-5962-hvcw is a HIGH denial of service vulnerability (General Security Weakness) affecting User agent parser libraries in the RubyGems ecosystem. The issue involves denial of service in uap-core when processing crafted user-agent strings. Remediation is available by upgrading affected packages to version 2.6.0.

GHSA-pcqq-5962-hvcw at a Glance

CVE Identifier N/A
GHSA Identifier GHSA-pcqq-5962-hvcw
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification General Security Weakness
Affected Product User agent parser
Package Ecosystem RubyGems
Published Date
Last Updated

How to Fix GHSA-pcqq-5962-hvcw

To remediate this vulnerability, upgrade all affected User agent parser dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

user_agent_parser fixed: 2.6.0 
Upgrade user_agent_parser to 2.6.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for user_agent_parser

How to Check if You Are Affected

To determine whether your application is affected by GHSA-pcqq-5962-hvcw, inspect your project dependencies for User agent parser:

inspect dependencies for user_agent_parser

Analyze the terminal output to locate any version of User agent parser in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.6.0), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under General Security Weakness. In User agent parser, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact Some regexes are vulnerable to regular expression denial of service (REDoS) due to overlapping capture groups. This allows remote attackers to overload a server by setting the User-Agent header in an HTTP(S) request to maliciously crafted long strings. ### Patches Please update `uap-ruby` to >= v2.6.0 ### For more information https://github.com/ua-parser/uap-core/security/advisories/GHSA-cmcx-xhr8-3w9p Reported in `uap-core` by Ben Caller @bcaller

GHSA-pcqq-5962-hvcw Affected User agent parser Versions

1 component(s)
Fixed Versions:
2.6.0
Product / Package Ecosystem Affected Versions Fixed Version
user_agent_parser
gem/user_agent_parser
RubyGems
< 2.6.0
2.6.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/ua-parser/uap-ruby/security/advisories/GHSA-pcqq-5962-hvcw
Security Fix Commit FIX COMMIT
https://github.com/ua-parser/uap-ruby/commit/2bb18268f4c5ba7d4ba0e21c296bf6437063da3a
User agent parser Source Repository REPOSITORY
https://github.com/rubysec/ruby-advisory-db/blob/master/gems/user_agent_parser/GHSA-pcqq-5962-hvcw.yml

Frequently Asked Questions

What is GHSA-pcqq-5962-hvcw?
GHSA-pcqq-5962-hvcw is a security vulnerability in User agent parser involving Denial of Service in uap-core when processing crafted User-Agent strings under General Security Weakness.
Which User agent parser versions are affected?
Affected versions include releases prior to 2.6.0 across affected packages: user_agent_parser.
What version fixes GHSA-pcqq-5962-hvcw?
Upgrading to 2.6.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is user_agent_parser affected?
Yes, user_agent_parser is affected in releases prior to 2.6.0. Upgrade your dependency to 2.6.0 or later.
What CWE is associated with GHSA-pcqq-5962-hvcw?
GHSA-pcqq-5962-hvcw is classified under General Security Weakness.
How can I check RubyGems dependencies for GHSA-pcqq-5962-hvcw?
Run the dependency tree command: 'inspect dependencies for user_agent_parser'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-pcqq-5962-hvcw",
  "modified" : "2025-05-22T17:12:55Z",
  "published" : "2020-03-10T18:02:49Z",
  "aliases" : [ ],
  "summary" : "Denial of Service in uap-core when processing crafted User-Agent strings",
  "details" : "### Impact\nSome regexes are vulnerable to regular expression denial of service (REDoS) due to overlapping capture groups. This allows remote attackers to overload a server by setting the User-Agent header in an HTTP(S) request to maliciously crafted long strings.\n\n### Patches\nPlease update `uap-ruby` to &gt;= v2.6.0\n\n### For more information\nhttps://github.com/ua-parser/uap-core/security/advisories/GHSA-cmcx-xhr8-3w9p\n\nReported in `uap-core` by Ben Caller @bcaller",
  "severity" : [ ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "user_agent_parser"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.6.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/ua-parser/uap-ruby/security/advisories/GHSA-pcqq-5962-hvcw"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/ua-parser/uap-ruby/commit/2bb18268f4c5ba7d4ba0e21c296bf6437063da3a"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/user_agent_parser/GHSA-pcqq-5962-hvcw.yml"
  } ],
  "database_specific" : {
    "cwe_ids" : [ ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2020-03-10T16:48:58Z",
    "nvd_published_at" : null
  }
}