CVE-2026-126353 Addressable: Regular Expression Denial of Service in Addressable templates with several exploded variables
Attacker-controlled URIs with many exploded variables can trigger regex backtracking in Addressable templates, exhausting threads in 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
- None listed
What is CVE-2026-126353?
CVE-2026-126353 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 containing several exploded variables generate ambiguous regular expressions that can divide a run of members among the variables in polynomially many ways. Template#match or Template#extract processing of an attacker-controlled URI can therefore consume a thread and cause denial of service. The flaw affects MRI Ruby before 3.2 and JRuby, TruffleRuby 40.0, and plus or number-sign expressions on MRI Ruby 3.2. MRI Ruby 3.3 and later, 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-2026-126353?
An affected version is only exploitable if your software calls Template#match or Template#extract. Many projects that include it are not exposed.
How do I fix CVE-2026-126353?
No fix has been published for CVE-2026-126353 yet. Limit exposure of the affected software until one is available.
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-2026-126353 being exploited?
There is no known exploitation of CVE-2026-126353 in the wild and no public exploit code.
Sources
Also known as GHSA-4w5q-wg7v-w6gp.