# CVE-2026-126352: Addressable URI template ReDoS denial of service

Source: https://junglewise.ai/threats/cve-2026-126352-addressable-is-an-alternative-implementation-to-the-uri  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-12. Updated: 2026-11-12  
License: CC BY 4.0 with a link back

CVE-2026-126352 · Severity: medium · CVSS 5.9 · Published 2026-11-12

Addressable is a Ruby library that parses and processes URIs and URI templates. Versions 2.3.0 through 2.9.0 contain a regular expression denial-of-service vulnerability where certain malformed URI templates cause catastrophic backtracking, allowing an attacker to crash applications using the library or make them unresponsive.

Technologies: [Addressable](https://junglewise.ai/threats/technologies/addressable-addressable), [addressable (RubyGems)](https://junglewise.ai/threats/technologies/addressable). Vendors: [Addressable](https://junglewise.ai/threats/vendors/addressable), [RubyGems](https://junglewise.ai/threats/vendors/rubygems).

## Quick answers

**Is CVE-2026-126352 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-126352 being exploited in the wild.

**How severe is CVE-2026-126352?** Medium severity, with a CVSS score of 5.9, published 12 November 2026.

**Which products and versions are affected?** Addressable 2.3.0 through 2.9.0; addressable (RubyGems) >= 2.3.0, < 2.9.1.

**Is there a fix for CVE-2026-126352?** Yes: fixed in 2.9.1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-126352 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-126352?** Check whether you run Addressable or addressable (RubyGems) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 2.9.1

## Technical details

The vulnerability exists in URI template matching logic (Template#match and Template#extract methods) where certain template patterns with multiple variables or adjacent expressions generate ambiguous regular expressions. On Ruby runtimes without regex match memoization (MRI before 3.2, JRuby, TruffleRuby), attacker-controlled URIs can cause polynomial or exponential regex backtracking, resulting in denial of service. URI parsing and Template#expand are unaffected.

## Affected products

- Addressable Addressable 2.3.0 through 2.9.0

## Identifiers

- CVE-2026-126352
- GHSA-9f42-57jx-vpp3

## Timeline

- 2026-11-12: disclosed

## References

- [https://github.com/sporkmonger/addressable/commit/f2b27b3ab252e56b3fa3519f7ebb491d54cf7b7c](https://github.com/sporkmonger/addressable/commit/f2b27b3ab252e56b3fa3519f7ebb491d54cf7b7c)
- [https://github.com/sporkmonger/addressable/releases/tag/addressable-2.9.1](https://github.com/sporkmonger/addressable/releases/tag/addressable-2.9.1)

## Related threats

- [Addressable URI.normalize_path path traversal and bypass](https://junglewise.ai/threats/cve-2026-126354-addressable-uri-normalization-resolves-some-dotted-path-segments)
- [Addressable URI path normalization denial of service](https://junglewise.ai/threats/cve-2026-126351-addressable-is-an-alternative-implementation-to-the-uri)
- [Addressable regular expression denial of service in URI template matching](https://junglewise.ai/threats/cve-2026-126350-addressable-is-an-alternative-implementation-to-the-uri)
- [Addressable display_uri can show misleading hosts containing bidi and invisible characters](https://junglewise.ai/threats/cve-2026-126349-addressable-is-an-alternative-implementation-to-the-uri)
- [Addressable punycode decoding host spoofing](https://junglewise.ai/threats/cve-2026-126348-addressable-is-an-alternative-implementation-to-the-uri)