CVE-2026-35611 (High) detected in addressable-2.8.9.gem

## CVE-2026-35611 - High Severity Vulnerability
Vulnerable Library - addressable-2.8.9.gem

Addressable is an alternative implementation to the URI implementation that is
part of Ruby's standard library. It is flexible, offers heuristic parsing, and
additionally provides extensive support for IRIs and URI templates.

Library home page: https://rubygems.org/gems/addressable-2.8.9.gem

Path to dependency file: /Gemfile.lock

Path to vulnerable library: /vendor/cache/addressable-2.8.9.gem

Dependency Hierarchy:
- manageiq-style-1.6.0.gem (Root Library)
- rubocop-performance-1.26.1.gem
- rubocop-1.85.1.gem
- mcp-0.9.0.gem
- json-schema-6.2.0.gem
- :x: **addressable-2.8.9.gem** (Vulnerable Library)

Found in base branch: master

Vulnerability Details

Addressable is an alternative implementation to the URI implementation that is part of Ruby's standard library. From 2.3.0 to before 2.9.0, within the URI template implementation in Addressable, two classes of URI template generate regular expressions vulnerable to catastrophic backtracking. Templates using the * (explode) modifier with any expansion operator (e.g., {foo*}, {+var*}, {#var*}, {/var*}, {.var*}, {;var*}, {?var*}, {&var*}) generate patterns with nested unbounded quantifiers that are O(2^n) when matched against a maliciously crafted URI. Templates using multiple variables with the + or # operators (e.g., {+v1,v2,v3}) generate patterns with O(n^k) complexity due to the comma separator being within the matched character class, causing ambiguous backtracking across k variables. When matched against a maliciously crafted URI, this can result in catastrophic backtracking and uncontrolled resource consumption, leading to denial of service. This vulnerability is fixed in 2.9.0.

Publish Date: 2026-04-07

URL: CVE-2026-35611

CVSS 3 Score Details (7.5)

Base Score Metrics:
- Exploitability Metrics:
- Attack Vector: Network
- Attack Complexity: Low
- Privileges Required: None
- User Interaction: None
- Scope: Unchanged
- Impact Metrics:
- Confidentiality Impact: None
- Integrity Impact: None
- Availability Impact: High

For more information on CVSS3 Scores, click here.

Suggested Fix

Type: Upgrade version

Release Date: 2026-04-07

Fix Resolution: https://github.com/sporkmonger/addressable.git - addressable-2.9.0

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Start with Gemfile.lock and vendor/cache/addressable-2.8.9.gem, then inspect the dependency hierarchy showing how addressable is brought in through rubocop and related gems. Update the vulnerable library to addressable-2.9.0 as indicated by the advisory, and verify that the lockfile and vendored dependency no longer contain 2.8.9.

Written by the indexing model from the issue text.