CVE-2026-126352 Addressable: Regular Expression Denial of Service in Addressable templates with multiple variables
Attacker-controlled URIs can trigger catastrophic regex backtracking in Addressable templates, causing denial of service in Ruby applications using it.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Harmful if only installed
- No
- Needs a specific call
- Yes
- Fix
- Available
What is CVE-2026-126352?
CVE-2026-126352 is a medium-severity denial of service vulnerability in sporkmonger addressable, published on 12 Nov 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Addressable is an alternative implementation to the URI implementation that is part of Ruby's standard library. From 2.3.0 until 2.9.1, URI templates with several variables in one expression or several adjacent expressions generate ambiguous regular expressions. Affected forms include multi-variable expressions using operators other than plus and number sign, large plus or number-sign expressions, and adjacent single-variable expressions. Template#match or Template#extract can backtrack polynomially or exponentially on attacker-controlled URIs, causing denial of service on MRI Ruby before 3.2 and JRuby, with the large plus and number-sign form also affecting MRI Ruby 3.2 and TruffleRuby 40.0. URI parsing and Template#expand are unaffected. This issue is fixed in version 2.9.1.
Weakness: CWE-1333
Which versions are affected by CVE-2026-126352?
1 open source package ship an affected version, including addressable.
An affected version is only exploitable if your software calls Template#match, Template#extract or Template#expand. Many projects that include it are not exposed.
| Package | Affected | Fixed in |
|---|---|---|
addressable RubyGems | From 2.3.0 | 2.9.1 |
How do I fix CVE-2026-126352?
Upgrade addressable to 2.9.1 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-126352 being exploited?
There is no known exploitation of CVE-2026-126352 in the wild and no public exploit code.
Sources
Also known as GHSA-9f42-57jx-vpp3.