Mailpit is an email testing tool and API for developers. Prior to version 1.28. 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.
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Affected Vendors & Products
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Fixes
Solution
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References
History
Sun, 18 Jan 2026 23:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Mailpit is an email testing tool and API for developers. Prior to version 1.28. 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. | |
| Title | Mailpit has SMTP Header Injection via Regex Bypass | |
| Weaknesses | CWE-150 CWE-93 |
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cvssV3_1
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Projects
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MITRE
Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-01-18T23:23:04.176Z
Reserved: 2026-01-16T15:46:40.841Z
Link: CVE-2026-23829
Vulnrichment
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NVD
Status : Received
Published: 2026-01-19T00:15:48.707
Modified: 2026-01-19T00:15:48.707
Link: CVE-2026-23829
Redhat
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OpenCVE Enrichment
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