CVE-2026-39971

Published: Apr 15, 2026 Last Modified: Apr 15, 2026
ExploitDB:
Other exploit source:
Google Dorks:
HIGH 7,2
Source: [email protected]
Attack Vector: network
Attack Complexity: low
Privileges Required: none
User Interaction: none
Scope: changed
Confidentiality: low
Integrity: low
Availability: none

Description

AI Translation Available

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.

EPSS (Exploit Prediction Scoring System)

Trend Analysis

EPSS (Exploit Prediction Scoring System)

Prevede la probabilità di sfruttamento basata su intelligence sulle minacce e sulle caratteristiche della vulnerabilità.

EPSS Score
0,0003
Percentile
0,1th
Updated

EPSS Score Trend (Last 2 Days)

113

Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')

Incomplete
Abstraction: Variant Structure: Simple
Common Consequences
Security Scopes Affected:
Integrity Access Control
Potential Impacts:
Modify Application Data Gain Privileges Or Assume Identity
Applicable Platforms
Technologies: Web Based, Web Server
View CWE Details
https://github.com/s9y/Serendipity/releases/tag/2.6.0
https://github.com/s9y/Serendipity/releases/tag/2.6.0
https://github.com/s9y/Serendipity/security/advisories/GHSA…
https://github.com/s9y/Serendipity/security/advisories/GHSA-458g-q4fh-mj6r