CVE-2026-2717

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

2026-04-21 19:13

Strategic Overview

Status: Unpatched
Affected Plugin: HTTP Headers
Affected Version: <= 1.19.2
CVSS: 5.5Medium
Weakness type: CWE-93 · Improper Neutralization of CRLF Sequences ('CRLF Injection')
CVE: CVE-2026-2717

At a glance

CVE-2026-2717 is a medium-severity Improper Neutralization of CRLF Sequences ('CRLF Injection') vulnerability in the HTTP Headers WordPress plugin, affecting versions <= 1.19.2. It carries a CVSS score of 5.5 (reachable over the network; low attack complexity; high availability impact). Exploitation requires an authenticated account at Administrator level or above. No fixed release has been reported yet; treat installations running this software as exposed. Disclosed April 2026, reported by Kai Aizen.

Vulnerability Overview

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.

Technical Analysis

The vector marks this flaw as remotely reachable over the network, with low attack complexity — no special timing or configuration is needed, and no interaction from a victim user. A successful exploit has high impact on availability.

CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')

The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.

Remediation

No known patch available. Please review the vulnerability's details in depth and employ mitigations based on your organization's risk tolerance. It may be best to uninstall the affected software and find a replacement.

How does WordSec protect against this?

No patched version is recorded yet, so there is nothing to update to; WordSec's vulnerability alerts flag this record the moment that changes.

Alerts

External References

https://www.cve.org/CVERecord?id=CVE-2026-2717 https://www.wordfence.com/threat-intel/vulnerabilities/id/7716e77f-e899-4046-9421-86fc0c36c245 https://nvd.nist.gov/vuln/detail/CVE-2026-2717

Related records

Other vulnerabilities in HTTP Headers

CVSS Vector

5.5

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

Base

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredHigh
User InteractionNone
ScopeUnchanged
ConfidentialityNone
IntegrityLow
AvailabilityHigh

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