CVE-2024-23185Network attack vector

Authenticated memory exhaustion via unbounded header buffer

Published Sep 10, 2024 · Updated Nov 4, 2025

Resource exhaustion in OX Dovecot Pro core 2.3.21 and earlier allows remote authenticated users to exhaust memory via IMAP APPEND. The lib-mail message-header-parser concatenates chunked header data into an unbounded full_value buffer, allowing memory use to grow with a single or folded header. Normal inbound MTA limits constrain that path, but an account able to issue APPEND can exhaust its own process and place memory pressure on the backend.

CVSS severity7.5
High
EPSS probability1.28%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in OX Dovecot Pro core 2.3.21 and earlier allows remote authenticated users to exhaust memory via IMAP APPEND. The lib-mail message-header-parser concatenates chunked header data into an unbounded full_value buffer, allowing memory use to grow with a single or folded header. Normal inbound MTA limits constrain that path, but an account able to issue APPEND can exhaust its own process and place memory pressure on the backend.

The record

CVE
CVE-2024-23185
Published
Sep 10, 2024
Updated
Nov 4, 2025
Vendor
Open-Xchange GmbH
Product
OX Dovecot Pro
Classifications
CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 10, 2024CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 2025Record 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=0 <=2.3.21

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Open-Xchange GmbH · OX Dovecot Proversion=0 <=2.3.21

Published CVSS scores

5.9Amazon LinuxCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5Open-Xchange GmbHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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