CVE-2026-67445Public exploitNetwork attack vectorHinoki check available

Service interruption via unbounded SMTP command buffering

Published Aug 20, 2026 · Updated Aug 20, 2026

Resource consumption in Mailpit before 1.30.4 allows remote attackers to interrupt service via an oversized SMTP command line. In internal/smtpd/smtpd.go, session.readLine() calls bufio.Reader.ReadString('\n') and fully buffers each command line before parseLine() or the RFC 5321 512-octet limit is enforced; the same reader also handles AUTH continuation input. Exposure requires reachability to the SMTP listener, which is enabled by default, and concurrent oversized commands can create memory pressure that degrades availability without demonstrated code execution or data access.

CVSS severity5.3
Medium
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Resource consumption in Mailpit before 1.30.4 allows remote attackers to interrupt service via an oversized SMTP command line. In internal/smtpd/smtpd.go, session.readLine() calls bufio.Reader.ReadString('\n') and fully buffers each command line before parseLine() or the RFC 5321 512-octet limit is enforced; the same reader also handles AUTH continuation input. Exposure requires reachability to the SMTP listener, which is enabled by default, and concurrent oversized commands can create memory pressure that degrades availability without demonstrated code execution or data access.

The record

CVE
CVE-2026-67445
Published
Aug 20, 2026
Updated
Aug 20, 2026
Vendor
Axllent
Product
Mailpit
Classifications
CWE-400, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.30.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Axllent · Mailpitversion=< 1.30.4

Published CVSS scores

5.3GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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