CVE-2026-23829
MEDIUM
GHSA-54wq-72mp-cq7c
CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Lifecycle Timeline
4Tags
Description
Mailpit is an email testing tool and API for developers. Prior to version 1.28.3, Mailpit's SMTP server is vulnerable to Header Injection due to an insufficient Regular Expression used to validate `RCPT TO` and `MAIL FROM` addresses. An attacker can inject arbitrary SMTP headers (or corrupt existing ones) by including carriage return characters (`\r`) in the email address. This header injection occurs because the regex intended to filter control characters fails to exclude `\r` and `\n` when used inside a character class. Version 1.28.3 fixes this issue.
Analysis
Header injection in Mailpit's SMTP server prior to version 1.28.3 allows unauthenticated remote attackers to inject or modify email headers by embedding carriage return characters in sender and recipient addresses due to insufficient regex validation. Public exploit code exists for this vulnerability, which could enable attackers to manipulate email routing, spoofing, or phishing attacks against users of the email testing tool. …
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Remediation
Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Vendor patch is available.
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