CVE-2026-42006Network attack vector

IMAP disruption via unbounded opening braces

Published May 12, 2026 · Updated May 12, 2026

Uncontrolled resource consumption in Open-Xchange Dovecot Pro through 2.4.3, 3.0.5, or 3.1.4 allows remote authenticated users to disrupt IMAP. The imap-login parser's incomplete brace-limit check rejects excessive closing braces but leaves opening braces unbounded, allowing crafted IMAP input to grow memory to the configured process limit. A valid IMAP account is required, and exhaustion causes availability loss without reported data disclosure or modification.

CVSS severity4.3
Medium
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in Open-Xchange Dovecot Pro through 2.4.3, 3.0.5, or 3.1.4 allows remote authenticated users to disrupt IMAP. The imap-login parser's incomplete brace-limit check rejects excessive closing braces but leaves opening braces unbounded, allowing crafted IMAP input to grow memory to the configured process limit. A valid IMAP account is required, and exhaustion causes availability loss without reported data disclosure or modification.

The record

CVE
CVE-2026-42006
Published
May 12, 2026
Updated
May 12, 2026
Vendor
Open-Xchange GmbH
Product
Dovecot Pro
Classifications
CWE-400, T1499.003
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 12, 2026CVE publishedPublication date reported by the CVE source.
  2. May 12, 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=0 <=2.4.3
  2. Affected versionversion=0 <=3.0.5
  3. Affected versionversion=0 <=3.1.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Open-Xchange GmbH · Dovecot Proversion=0 <=2.4.3; version=0 <=3.0.5; version=0 <=3.1.4

Published CVSS scores

7.5Red HatCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.3Open-XchangeCVSS:3.1/AV:N/AC:L/PR:L/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.003Application Exhaustion Flood

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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