# CVE-2026-126351: Addressable: Denial of service in URI path normalization

> Attacker-controlled URIs normalized by Addressable can cause quadratic work and deny service to Ruby apps joining untrusted paths.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **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 (`Addressable::URI.normalize_path`, `URI#normalize`, `URI#normalized_path`)
- **Fix available:** Yes
- **Published:** 12 Nov 2026
- **Updated:** 12 Nov 2026
- **Also known as:** AZL-113813, GHSA-qq38-m9mg-xjj5

## What is CVE-2026-126351?

CVE-2026-126351 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. Prior to 2.9.1, Addressable::URI.normalize_path repeatedly scans and rewrites paths while removing only one nested dot segment per pass, producing quadratic work. URI#normalize, URI#normalized_path, URI#join, URI#==, and URI#=== inherit the behavior, so processing a sufficiently long attacker-controlled URI can consume a worker thread and cause denial of service on every Ruby implementation. URI.parse alone and code that never normalizes, compares, or joins untrusted URIs are unaffected. This issue is fixed in version 2.9.1.

Weakness: CWE-407 (Inefficient Algorithmic Complexity)

## Which versions are affected by CVE-2026-126351?

1 open source package ship an affected version, including addressable.

An affected version is only exploitable if your software calls Addressable::URI.normalize_path, URI#normalize or URI#normalized_path. Many projects that include it are not exposed.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `addressable` | RubyGems | All versions | 2.9.1 |

## How do I fix CVE-2026-126351?

Upgrade addressable to 2.9.1 or later.

## Is CVE-2026-126351 being exploited?

There is no known exploitation of CVE-2026-126351 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-126351 and fix it if it is affected.

What it is: CVE-2026-126351 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.
Exploitation: There is no known exploitation of CVE-2026-126351 in the wild and no public exploit code.
Exposure: An affected version is only exploitable if your software calls Addressable::URI.normalize_path, URI#normalize or URI#normalized_path. Many projects that include it are not exposed.

Affected packages and fixed versions:
- addressable (RubyGems): affected all versions; fixed in 2.9.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
   If an affected version is present, also search the code for calls to Addressable::URI.normalize_path, URI#normalize or URI#normalized_path and report whether any exist.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-126351/ (Markdown: https://insights.sbomify.com/CVE-2026-126351/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-126351
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-126351
- OSV: https://osv.dev/vulnerability/CVE-2026-126351

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-126351/
Summaries are generated and may contain mistakes; the official description above is the record.