CVE-2026-126350 Addressable: Regular Expression Denial of Service in Addressable templates with certain exploded expressions
Attacker-controlled URIs with certain exploded template expressions cause catastrophic regex backtracking in Addressable, denying service to Ruby apps 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-2026-126350?
CVE-2026-126350 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 template expressions using the explode modifier with the slash, dot, semicolon, question-mark, or ampersand operators generate ambiguous regular expressions. When Template#match or Template#extract processes an attacker-controlled URI beginning with the operator's leading character, optional member separators allow catastrophic backtracking and denial of service on MRI Ruby before 3.2 and JRuby. Addressable 2.9.0 incompletely remediated the earlier template issue because its tests did not reach these operator-prefixed paths. 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-2026-126350?
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-2026-126350?
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-2026-126350 being exploited?
There is no known exploitation of CVE-2026-126350 in the wild and no public exploit code.
Sources
Also known as GHSA-j82w-28jv-3pmj.