Resource exhaustion in Axllent Mailpit
CVE-2026-67445
Mailpit is an email testing tool and API for developers. Prior to 1.30.4, Mailpit reads SMTP commands through internal/smtpd/smtpd.go session.readLine() using bufio.Reader.ReadString before session.parseLine() parses the verb or the RFC 5321 512-octet command-line limit is enforced. An unauthenticated remote SMTP client can send an oversized single command line that is fully allocated before syntax rejection or timeout, and the normal MaxMessageSize and DATA limits do not apply to this pre-DATA path. The same command reader is used by handleAuthLogin(), handleAuthPlain(), and handleAuthCramMD5() continuation lines, so concurrent oversized inputs can create memory pressure and reduce service availability. This issue is fixed in version 1.30.4.
Vulnerability class: DoS (Denial of Service)
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
Affected products
- Axllent Mailpit — versions < 1.30.4
Weakness classification (CWE)
References
- https://github.com/axllent/mailpit/commit/993bed95b3c74d95231af93bd0e0d4c3d5b4db4d (x_refsource_MISC)
- https://github.com/axllent/mailpit/releases/tag/v1.30.4 (x_refsource_MISC)
- https://github.com/axllent/mailpit/security/advisories/GHSA-w878-pj84-3j5v (x_refsource_CONFIRM)
Frequently asked questions
- What is CVE-2026-67445?
- CVE-2026-67445 is a medium-severity vulnerability in Axllent Mailpit, classified under Uncontrolled Resource Consumption. CVSS score: 5.3/10. Published 2026-08-20.
- How severe is CVE-2026-67445?
- Medium severity. CVSS v3 base score is 5.3 out of 10.