CVE-2026-30227
published 2026-03-06CVE-2026-30227: 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…
PriorityP334medium5.3CVSS 3.1
AVNACLPRNUINSUCNILAN
EPSS
1.08%
61.1th percentile
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 , making CRLF injection in command arguments particularly dangerous. This issue has been patched in version 4.15.1.
Affected
2 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| jstedfast | mimekit | < 4.15.1 | 4.15.1 |
| jstedfast | mimekit | >= 0 < 4.15.1 | 4.15.1 |
CVSS provenance
nvdv3.15.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
nvdv4.06.9MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Stop checking back — get the weekly exploitation signal.
Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.
GHSA
MimeKit has CRLF Injection in Quoted Local-Part that Enables SMTP Command Injection and Email Forgery
ghsa·2026-03-05
CVE-2026-30227 [MEDIUM] CWE-93 MimeKit has CRLF Injection in Quoted Local-Part that Enables SMTP Command Injection and Email Forgery
MimeKit has CRLF Injection in Quoted Local-Part that Enables SMTP Command Injection and Email Forgery
### Summary
A CRLF Injection vulnerability in MimeKit 4.15.0 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)
OSV
MimeKit has CRLF Injection in Quoted Local-Part that Enables SMTP Command Injection and Email Forgery
osv·2026-03-05
CVE-2026-30227 [MEDIUM] MimeKit has CRLF Injection in Quoted Local-Part that Enables SMTP Command Injection and Email Forgery
MimeKit has CRLF Injection in Quoted Local-Part that Enables SMTP Command Injection and Email Forgery
### Summary
A CRLF Injection vulnerability in MimeKit 4.15.0 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)
No detection rules found.
No public exploits indexed.
2026-03-06
Published