CVE-2026-42006: Uncontrolled Resource Consumption in Open-Xchange GmbH OX Dovecot Pro
An attacker can cause uncontrolled memory usage with excessive bracing over IMAP. The fix in CVE-2026-27857 was incomplete, only blocking one way of doing this, so there was still another way left open. In particular, the fix was for closing braces, but you could still use open braces to bypass the limit. Using excessive bracing, attacker can cause memory usage up to configured memory limit. Install fixed version, or configure vsz_limit for imap process to low value. No publicly available exploits are known.
AI Analysis
Technical Summary
This vulnerability involves uncontrolled resource consumption (CWE-770) in OX Dovecot Pro's IMAP server due to excessive use of braces in IMAP commands. The prior fix (CVE-2026-27857) addressed only excessive closing braces, but attackers can still use excessive opening braces to bypass limits and cause high memory usage. The impact is denial of service through resource exhaustion. Red Hat has released updated Dovecot packages for Red Hat Enterprise Linux 10.0 Extended Update Support that fix this issue. The vulnerability has a CVSS 3.1 base score of 4.3 (medium severity) with network attack vector, low complexity, requiring low privileges, no user interaction, and impacts availability only.
Potential Impact
An attacker with low privileges can cause the IMAP server process to consume excessive memory by sending IMAP commands with excessive opening braces. This can lead to denial of service by exhausting memory resources up to the configured memory limit of the IMAP process. There is no impact on confidentiality or integrity. No known public exploits exist.
Mitigation Recommendations
Red Hat has released security updates for Dovecot that fix this vulnerability. Users should apply the updated packages as provided in the Red Hat advisory RHSA-2026:42091 for Red Hat Enterprise Linux 10.0 Extended Update Support. Alternatively, configuring the vsz_limit for the IMAP process to a low value can mitigate the impact by limiting memory usage. Patch status is confirmed by Red Hat advisory; a fix is available and should be applied.
CVE-2026-42006: Uncontrolled Resource Consumption in Open-Xchange GmbH OX Dovecot Pro
Description
An attacker can cause uncontrolled memory usage with excessive bracing over IMAP. The fix in CVE-2026-27857 was incomplete, only blocking one way of doing this, so there was still another way left open. In particular, the fix was for closing braces, but you could still use open braces to bypass the limit. Using excessive bracing, attacker can cause memory usage up to configured memory limit. Install fixed version, or configure vsz_limit for imap process to low value. No publicly available exploits are known.
CVSS v3.1
Score 4.3medium
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability involves uncontrolled resource consumption (CWE-770) in OX Dovecot Pro's IMAP server due to excessive use of braces in IMAP commands. The prior fix (CVE-2026-27857) addressed only excessive closing braces, but attackers can still use excessive opening braces to bypass limits and cause high memory usage. The impact is denial of service through resource exhaustion. Red Hat has released updated Dovecot packages for Red Hat Enterprise Linux 10.0 Extended Update Support that fix this issue. The vulnerability has a CVSS 3.1 base score of 4.3 (medium severity) with network attack vector, low complexity, requiring low privileges, no user interaction, and impacts availability only.
Potential Impact
An attacker with low privileges can cause the IMAP server process to consume excessive memory by sending IMAP commands with excessive opening braces. This can lead to denial of service by exhausting memory resources up to the configured memory limit of the IMAP process. There is no impact on confidentiality or integrity. No known public exploits exist.
Mitigation Recommendations
Red Hat has released security updates for Dovecot that fix this vulnerability. Users should apply the updated packages as provided in the Red Hat advisory RHSA-2026:42091 for Red Hat Enterprise Linux 10.0 Extended Update Support. Alternatively, configuring the vsz_limit for the IMAP process to a low value can mitigate the impact by limiting memory usage. Patch status is confirmed by Red Hat advisory; a fix is available and should be applied.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- OX
- Date Reserved
- 2026-04-23T11:15:21.199Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
- Vendor Advisory Urls
- [{"url":"https://access.redhat.com/security/cve/CVE-2026-42006","vendor":"Red Hat"}]
Threat ID: 6a0333e5cbff5d8610ef1d37
Added to database: 05/12/2026, 14:06:29 UTC
Last enriched: 07/25/2026, 21:45:54 UTC
Last updated: 07/31/2026, 19:30:16 UTC
Views: 79
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