# CVE-2026-126079: Action View: Possible XSS vulnerability in Action View text helpers


- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 10 Nov 2026
- **Updated:** 10 Nov 2026
- **Also known as:** DEBIAN-CVE-2026-126079, GHSA-2p2f-4rq4-gjwc, UBUNTU-CVE-2026-126079

## What is CVE-2026-126079?

CVE-2026-126079 is a medium-severity vulnerability in rails, published on 10 Nov 2026. 

### Official description

Action View is a framework for handling view template lookup and rendering and provides view helpers for building HTML. Prior to 8.1.4.1 and 8.0.5.2, with the HTML5 sanitizer (Rails::HTML5::Sanitizer, the default vendor on CRuby for applications using load_defaults 7.1 or later), Nokogiri before 1.19.5 serializes < and > unescaped inside attribute values. The Action View text helpers highlight and simple_format sanitize their input and then process the resulting HTML as a string: highlight splits it on tag boundaries to insert matches, and simple_format splits it into paragraphs on blank lines. An unescaped > or a blank line inside an attribute value could cause markup in that value, which the sanitizer left inert, to be emitted as live elements in the helper's html_safe output, possibly leading to XSS. Applications that use the HTML5 sanitizer and pass untrusted text to highlight, or to simple_format with html_options, are affected. This issue is fixed in versions 8.1.4.1 and 8.0.5.2.

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

## Which versions are affected by CVE-2026-126079?

2 open source packages ship an affected version, including actionview.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `actionview` | RubyGems | All versions | 8.0.5.2 |
| `actionview` | RubyGems | From 8.1.0.beta1 | 8.1.4.1 |

## How do I fix CVE-2026-126079?

Upgrade actionview to a fixed version for your release line: 8.0.5.2 or 8.1.4.1.

## Is CVE-2026-126079 being exploited?

There is no known exploitation of CVE-2026-126079 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-126079 and fix it if it is affected.

What it is: CVE-2026-126079 is a medium-severity vulnerability in rails, published on 10 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-126079 in the wild and no public exploit code.

Affected packages and fixed versions:
- actionview (RubyGems): affected all versions; fixed in 8.0.5.2
- actionview (RubyGems): affected from 8.1.0.beta1; fixed in 8.1.4.1

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-2026-126079/ (Markdown: https://insights.sbomify.com/CVE-2026-126079/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-126079
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-126079
- OSV: https://osv.dev/vulnerability/CVE-2026-126079

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-126079/
Summaries are generated and may contain mistakes; the official description above is the record.