CVE-2026-67447Public exploitNetwork attack vectorHinoki check available

Service interrupt via oversized SMTP DATA buffering

Published Aug 20, 2026 · Updated Aug 20, 2026

Denial of service in Mailpit 1.30.0 through 1.30.4 allows remote attackers to cause memory pressure via an oversized SMTP DATA line. In internal/smtpd/smtpd.go, readData() calls bufio.Reader.ReadBytes('\n') before checking len(data)+len(line) against Server.MaxSize, so one newline-terminated line is fully allocated before rejection. SMTP is enabled by default; an unauthenticated client can repeat oversized single-line DATA requests to push memory use beyond the configured MaxMessageSize and interrupt service availability.

CVSS severity5.3
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Denial of service in Mailpit 1.30.0 through 1.30.4 allows remote attackers to cause memory pressure via an oversized SMTP DATA line. In internal/smtpd/smtpd.go, readData() calls bufio.Reader.ReadBytes('\n') before checking len(data)+len(line) against Server.MaxSize, so one newline-terminated line is fully allocated before rejection. SMTP is enabled by default; an unauthenticated client can repeat oversized single-line DATA requests to push memory use beyond the configured MaxMessageSize and interrupt service availability.

The record

CVE
CVE-2026-67447
Published
Aug 20, 2026
Updated
Aug 20, 2026
Vendor
Axllent
Product
Mailpit
Classifications
CWE-770, CAPEC-130, T1499.003
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=>= 1.30.0, < 1.30.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Axllent · Mailpitversion=>= 1.30.0, < 1.30.5

Published CVSS scores

5.3GitHub, Inc.CVSS: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-770Allocation of Resources Without Limits or Throttling
CAPEC-130Excessive Allocation
T1499.003Application Exhaustion Flood

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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