MimeKit is a C# library which may be used for the creation and parsing of messages using the Multipurpose Internet Mail Extension (MIME), as defined by numerous IETF specifications. Prior to version 4.15.1, a CRLF injection vulnerability in MimeKit allows an attacker to embed \r\n into the SMTP envelope address local-part (when the local-part is a quoted-string). This is non-compliant with RFC 5321 and can result in SMTP command injection (e.g., injecting additional RCPT TO / DATA / RSET commands) and/or mail header injection, depending on how the application uses MailKit/MimeKit to construct and send messages. The issue becomes exploitable when the attacker can influence a MailboxAddress (MAIL FROM / RCPT TO) value that is later serialized to an SMTP session. RFC 5321 explicitly defines the SMTP mailbox local-part grammar and does not permit CR (13) or LF (10) inside Quoted-string (qtextSMTP and quoted-pairSMTP ranges exclude control characters). SMTP commands are terminated by <CRLF>, making CRLF injection in command arguments particularly dangerous. This issue has been patched in version 4.15.1.

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Source ID Title
Github GHSA Github GHSA GHSA-g7hc-96xr-gvvx MimeKit has CRLF Injection in Quoted Local-Part that Enables SMTP Command Injection and Email Forgery
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Thu, 12 Mar 2026 15:45:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:jstedfast:mimekit:*:*:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N'}


Mon, 09 Mar 2026 21:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Mon, 09 Mar 2026 10:15:00 +0000

Type Values Removed Values Added
First Time appeared Jstedfast
Jstedfast mimekit
Vendors & Products Jstedfast
Jstedfast mimekit

Fri, 06 Mar 2026 21:15:00 +0000

Type Values Removed Values Added
Description MimeKit is a C# library which may be used for the creation and parsing of messages using the Multipurpose Internet Mail Extension (MIME), as defined by numerous IETF specifications. Prior to version 4.15.1, a CRLF injection vulnerability in MimeKit allows an attacker to embed \r\n into the SMTP envelope address local-part (when the local-part is a quoted-string). This is non-compliant with RFC 5321 and can result in SMTP command injection (e.g., injecting additional RCPT TO / DATA / RSET commands) and/or mail header injection, depending on how the application uses MailKit/MimeKit to construct and send messages. The issue becomes exploitable when the attacker can influence a MailboxAddress (MAIL FROM / RCPT TO) value that is later serialized to an SMTP session. RFC 5321 explicitly defines the SMTP mailbox local-part grammar and does not permit CR (13) or LF (10) inside Quoted-string (qtextSMTP and quoted-pairSMTP ranges exclude control characters). SMTP commands are terminated by <CRLF>, making CRLF injection in command arguments particularly dangerous. This issue has been patched in version 4.15.1.
Title MimeKit: CRLF Injection in Quoted Local-Part Enables SMTP Command Injection and Email Forgery
Weaknesses CWE-93
References
Metrics cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-03-09T20:54:29.184Z

Reserved: 2026-03-04T17:23:59.797Z

Link: CVE-2026-30227

cve-icon Vulnrichment

Updated: 2026-03-09T20:47:36.375Z

cve-icon NVD

Status : Analyzed

Published: 2026-03-06T21:16:16.607

Modified: 2026-03-12T15:34:59.480

Link: CVE-2026-30227

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-03-09T10:06:53Z

Weaknesses