Description
Serendipity is a PHP-powered weblog engine. In versions 2.6-beta2 and below, the email sending functionality in include/functions.inc.php inserts $_SERVER['HTTP_HOST'] directly into the Message-ID SMTP header without validation, and the existing sanitization function serendipity_isResponseClean() is not called on HTTP_HOST before embedding it. An attacker who can control the Host header during an email-triggering action such as comment notifications or subscription emails can inject arbitrary SMTP headers into outgoing emails. This enables identity spoofing, reply hijacking via manipulated Message-ID threading, and email reputation abuse through the attacker's domain being embedded in legitimate mail headers. This issue has been fixed in version 2.6.0.
INFO
Published Date :
2026-04-14T23:35:49.305Z
Last Modified :
2026-04-14T23:35:49.305Z
Source :
GitHub_M
AFFECTED PRODUCTS
The following products are affected by CVE-2026-39971 vulnerability.
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REFERENCES
Here, you will find a curated list of external links that provide in-depth information to CVE-2026-39971.
