dbcve.org
AddressableApplication · Addressable Project

CVE-2026-35611

HIGH · 7.5 CVSS v3.1 Published 2026-04-07
Fix available
A fix is available. Upgrade to 2.9.0 or later.
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
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.

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 · high confidence

The Addressable gem versions 2.3.0 to before 2.9.0 contains a regex DoS vulnerability in its URI template implementation. Specifically, templates using the * (explode) modifier with any expansion operator generate regex patterns with nested unbounded quantifiers causing O(2^n) complexity, while templates with multiple variables using + or # operators create O(n^k) complexity patterns. Both can cause catastrophic backtracking when matched against maliciously crafted URIs.

MitigationUpgrade Addressable gem to version 2.9.0 or later to resolve the vulnerability.

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
AddressableApplication
Affected:>= 2.3.0, < 2.9.0

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:3.1/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 Addressable gem version
    Run `gem list addressable` or check your Gemfile.lock for the installed version of the addressable gem
    Affected if Version is 2.3.0 or higher but lower than 2.9.0
  2. Identify URI template usage
    Search codebase for references to Addressable::URI::Template or require 'addressable/template' in Ruby files
    Affected if The codebase uses Addressable's URI template functionality
  3. Detect vulnerable template patterns
    Search for template definitions using the *, +, or # operators in expansion expressions, such as {?params*}, {+path+}, or {#var#} patterns in your code or configuration files
    Affected if Templates contain explode (*) modifier or +/# operators with multiple variables
  4. Verify runtime dependency
    Run `bundle show addressable` in your project directory to confirm the loaded version at runtime
    Affected if The runtime version matches the affected range (>=2.3.0, <2.9.0)

You are affected if Addressable gem version is 2.3.0 or higher but below 2.9.0 AND your application uses URI templates with explode (*) modifiers or plus (#) operators on multiple variables.

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.

dbcve · scoped
Upgrade available Upgrade to 2.9.0 or later
Fixed in 2.9.0
Interim mitigation

Upgrade Addressable gem to version 2.9.0 or later to resolve the vulnerability.

Recommended fix High confidence

2.9.0

  1. Check current Addressable gem version by running `gem list addressable` or inspecting your Gemfile.lock
  2. Update the Addressable gem to version 2.9.0 or later using `gem install addressable -v '>= 2.9.0'` or by updating your Gemfile with `gem 'addressable', '>= 2.9.0'` and running `bundle update addressable`
  3. Verify the update was successful by running `gem list addressable` to confirm version 2.9.0 or higher is installed
  4. If using Bundler, run `bundle exec` commands to ensure the updated gem is used in your application

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Addressable Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,376.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-35611 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2026-35611 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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