CVE-2026-34752Public exploitNetwork attack vector

Unauthenticated SMTP crash via prototype header lookup

Published Apr 2, 2026 · Updated Apr 2, 2026

Uncaught exception handling in Haraka before 3.1.4 allows remote attackers to crash an SMTP worker by sending a crafted email header. The header parser stores names in a plain object, so the inherited proto value bypasses nullish assignment and receives an invalid push call. The resulting TypeError exits the process; single-process mode stops the server, while cluster mode restarts the worker and drops its active sessions.

CVSS severity8.7
High
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncaught exception handling in Haraka before 3.1.4 allows remote attackers to crash an SMTP worker by sending a crafted email header. The header parser stores names in a plain object, so the inherited proto value bypasses nullish assignment and receives an invalid push call. The resulting TypeError exits the process; single-process mode stops the server, while cluster mode restarts the worker and drops its active sessions.

The record

CVE
CVE-2026-34752
Published
Apr 2, 2026
Updated
Apr 2, 2026
Vendor
Haraka
Product
Haraka
Classifications
CWE-248, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 2, 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=< 3.1.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Haraka · Harakaversion=< 3.1.4

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
8.7GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

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-248Uncaught Exception
T1499.004Application or System Exploitation

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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