CVE-2026-67445
Mailpit: SMTP command parser buffers unbounded command lines before syntax rejection
Description
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.
INFO
Published Date :
Aug. 20, 2026, 9:17 p.m.
Last Modified :
Oct. 18, 2026, 8:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | MITRE-CVE |
Solution
- Update Mailpit to version 1.30.4 or newer.
- Monitor Mailpit for resource exhaustion.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-67445.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-67445 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-67445
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-67445 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-67445 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 18, 2026
Action Type Old Value New Value Added Translation Title: mailpit de axllent, Description: Mailpit es una herramienta de prueba de correo electrónico y API para desarrolladores. Antes de la versión 1.30.4, Mailpit lee comandos SMTP a través de internal/smtpd/smtpd.go session.readLine() utilizando bufio.Reader.ReadString antes de que session.parseLine() analice el verbo o se aplique el límite de línea de comando de 512 octetos de RFC 5321. Un cliente SMTP remoto no autenticado puede enviar una única línea de comando de tamaño excesivo que se asigna completamente antes del rechazo de sintaxis o el tiempo de espera, y los límites normales de MaxMessageSize y DATA no se aplican a esta ruta pre-DATA. El mismo lector de comandos es utilizado por las líneas de continuación de handleAuthLogin(), handleAuthPlain() y handleAuthCramMD5(), por lo que las entradas concurrentes de tamaño excesivo pueden crear presión en la memoria y reducir la disponibilidad del servicio. Este problema se soluciona en la versión 1.30.4. -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 21, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-67445', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-21T21:09:33.233187Z'} -
New CVE Received by [email protected]
Aug. 20, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'axllent', 'product': 'mailpit', 'versions': [{'status': 'affected', 'version': '< 1.30.4'}]}] Added Description 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Added CWE CWE-400 Added Reference https://github.com/axllent/mailpit/commit/993bed95b3c74d95231af93bd0e0d4c3d5b4db4d Added Reference https://github.com/axllent/mailpit/releases/tag/v1.30.4 Added Reference https://github.com/axllent/mailpit/security/advisories/GHSA-w878-pj84-3j5v