CVE-2026-30227: MimeKit: CRLF Injection in Quoted Local-Part Enables SMTP Command Injection and Email Forgery
jstedfast · MimeKit
Affected: jstedfast MimeKit · Exploitation: possible (1 to 10%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 68% of scored CVEs
DescriptionCVE.org
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.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- jstedfast · MimeKit< 4.15.1
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Possible (1 to 10%). EPSS between 1% and 10%.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Published
- March 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-30227 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.