What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-04-22 · updated 2026-06-17
• Weakness: CWE-93

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.

Affected products

• zinoui HTTP Headers: through 1.19.2

References

• https://plugins.trac.wordpress.org/browser/http-headers/tags/1.19.2/http-headers.php#L1098
• https://plugins.trac.wordpress.org/browser/http-headers/tags/1.19.2/http-headers.php#L745
• https://plugins.trac.wordpress.org/browser/http-headers/trunk/http-headers.php#L1098
• https://plugins.trac.wordpress.org/browser/http-headers/trunk/http-headers.php#L745
• https://www.wordfence.com/threat-intel/vulnerabilities/id/7716e77f-e899-4046-9421-86fc0c36c245?source=cve

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