# CVE-2026-2717: HTTP Headers <= 1.19.2 - Authenticated (Administrator+) CRLF Injection via Custom Header Values

> Administrators can inject CRLF characters into Apache configuration files via custom headers, causing parse errors and site-wide denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 22 Apr 2026
- **Updated:** 22 Apr 2026
- **Also known as:** GHSA-r256-59w3-3gr2

## What is CVE-2026-2717?

CVE-2026-2717 is a medium-severity vulnerability in zinoui HTTP Headers, published on 22 Apr 2026. An attacker needs administrator access to exploit it, with no action from the victim.

### Official description

The HTTP Headers plugin for WordPress is vulnerable to CRLF Injection in all versions up to, and including, 1.19.2. This is due to insufficient sanitization of custom header name and value fields before writing them to the Apache .htaccess file via `insert_with_markers()`. This makes it possible for authenticated attackers, with Administrator-level access and above, to inject arbitrary newline characters and additional Apache directives into the .htaccess configuration file via the 'Custom Headers' settings, leading to Apache configuration parse errors and potential site-wide denial of service.

Weakness: CWE-93 (Improper Neutralization of CRLF Sequences)

## Which versions are affected by CVE-2026-2717?


## How do I fix CVE-2026-2717?

No fix has been published for CVE-2026-2717 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-2717 being exploited?

There is no known exploitation of CVE-2026-2717 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-2717 and fix it if it is affected.

What it is: CVE-2026-2717 is a medium-severity vulnerability in zinoui HTTP Headers, published on 22 Apr 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-2717 in the wild and no public exploit code.

Affected product: zinoui HTTP Headers. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-2717/ (Markdown: https://insights.sbomify.com/CVE-2026-2717/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-2717
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-2717
- OSV: https://osv.dev/vulnerability/CVE-2026-2717

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-2717/
Summaries are generated and may contain mistakes; the official description above is the record.