# CVE-2026-33167: Rails has a possible XSS vulnerability in its Action Pack debug exceptions

> Attackers can inject arbitrary HTML and JavaScript via crafted exception messages in Rails debug pages, affecting developers using default development settings.

- **Severity:** Low 1.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 23 Mar 2026
- **Updated:** 24 Mar 2026
- **Also known as:** GHSA-pgm4-439c-5jp6, UBUNTU-CVE-2026-33167

## What is CVE-2026-33167?

CVE-2026-33167 is a low-severity cross-site scripting vulnerability in Rubyonrails Rails, published on 23 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Action Pack is a Rubygem for building web applications on the Rails framework. In versions on the 8.1 branch prior to 8.1.2.1, the debug exceptions page does not properly escape exception messages. A carefully crafted exception message could inject arbitrary HTML and JavaScript into the page, leading to XSS. This affects applications with detailed exception pages enabled (`config.consider_all_requests_local = true`), which is the default in development. Version 8.1.2.1 contains a patch.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-33167?

2 open source packages ship an affected version, including actionpack. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `actionpack` | RubyGems | From 8.1.0 | 8.1.2.1 |
| `actionpack` | RubyGems | From 8.1.0 | 8.1.2.1 |

Products: Rubyonrails Rails.

## How do I fix CVE-2026-33167?

Upgrade actionpack to 8.1.2.1 or later.

## Is CVE-2026-33167 being exploited?

There is no known exploitation of CVE-2026-33167 in the wild and no public exploit code.

## Other vulnerabilities in Rubyonrails Rails

- [CVE-2013-0277](https://insights.sbomify.com/CVE-2013-0277/): Active Record contains deserialization of arbitrary YAML (critical 10.0)
- [CVE-2017-17916](https://insights.sbomify.com/CVE-2017-17916/): SQL injection in n/a (high 8.1)
- [CVE-2017-17917](https://insights.sbomify.com/CVE-2017-17917/): SQL injection in n/a (high 8.1)
- [CVE-2026-33195](https://insights.sbomify.com/CVE-2026-33195/): Rails Active Storage has possible Path Traversal in DiskService (high 8.0)
- [CVE-2024-26142](https://insights.sbomify.com/CVE-2024-26142/): Rails possible ReDoS vulnerability in Accept header parsing in Action Dispatch (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33167 and fix it if it is affected.

What it is: CVE-2026-33167 is a low-severity cross-site scripting vulnerability in Rubyonrails Rails, published on 23 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-33167 in the wild and no public exploit code.

Affected packages and fixed versions:
- actionpack (RubyGems): affected from 8.1.0; fixed in 8.1.2.1
- actionpack (RubyGems): affected from 8.1.0; fixed in 8.1.2.1

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.
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-2026-33167/ (Markdown: https://insights.sbomify.com/CVE-2026-33167/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33167
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33167
- OSV: https://osv.dev/vulnerability/CVE-2026-33167

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33167/
Summaries are generated and may contain mistakes; the official description above is the record.