CVE-2026-2717: 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 saniti...

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.

Metrics

CVSS 3.1

5.5/10

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:H

EPSS Probability

0.47%

37.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-93

References

Timeline

Published: Apr 22, 2026
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-2717?

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.

How severe is CVE-2026-2717?

CVE-2026-2717 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.47% probability of exploitation in the next 30 days.

How do I fix CVE-2026-2717?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.