Security readout for executives and security teams
Plain-English summary
CVE-2026-42006 is a denial-of-service issue in OX Dovecot Pro IMAP handling. A remote unauthenticated attacker can drive memory use up to the configured limit, potentially disrupting mail access. The prior fix for CVE-2026-27857 was incomplete.
Executive priority
Treat as a high-priority availability risk for mail infrastructure, especially where IMAP is externally reachable. It is not described as data theft or code execution, but a successful denial of service could interrupt email access and business operations.
Technical view
The issue involves excessive IMAP bracing. The earlier fix blocked one closing-brace path, but open braces could still bypass the limit. This permits uncontrolled memory consumption up to the configured process limit. CVSS 3.1 is 7.5: network reachable, low complexity, no privileges, no user interaction, availability impact only.
Likely exposure
Exposure is most relevant to organizations running OX Dovecot Pro with IMAP reachable by untrusted users or the internet. The bundle does not provide a clear affected version range beyond the vendor/product entry, so teams should confirm installed versions against Open-Xchange guidance.
Exploitation context
The source bundle says no publicly available exploits are known, and KEV status is false. The vulnerability is still operationally important because IMAP is commonly exposed and the attack requires no privileges or user interaction. Do not assume active exploitation without additional evidence.
Researcher notes
The key nuance is incomplete remediation of CVE-2026-27857: closing-brace limiting did not cover open-brace behavior. Evidence supports CWE-400/CWE-770 resource exhaustion. Version impact details are limited in the provided bundle, so validation should rely on vendor and distributor advisories.
Mitigation direction
- Install the fixed OX Dovecot Pro version identified by Open-Xchange guidance.
- Configure a low vsz_limit for the imap process if patching is delayed.
- Check Red Hat and vendor advisories for package-specific status.
- Prioritize systems with internet-facing or broadly reachable IMAP services.
- Monitor IMAP service memory pressure and availability during remediation.
Validation and detection
- Inventory OX Dovecot Pro deployments and confirm IMAP exposure.
- Compare installed package versions against Open-Xchange advisory data.
- Verify imap process vsz_limit is configured to limit memory impact.
- Review logs and monitoring for abnormal IMAP memory growth or crashes.
- Track Red Hat Bugzilla and CSAF/VEX updates for affected-status changes.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-400: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-770: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-42006 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADPCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L2.81.4OXVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Base CVSS 3.1 score
4.3MediumVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Made public.
- CVE publishedCVE Program
The CVE record was published.
- ADP timelineredhat-SADP
Reported to Red Hat.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-05-12T14:02:01.841Z: Reported to Red Hat.
- 2026-05-12T13:28:46.922Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0002.jsonCVE reference, OX · vendor-advisory
- https://access.redhat.com/security/cve/CVE-2026-42006CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2476476CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42006.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Uncontrolled Resource Consumption
Uncontrolled Resource Consumption represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Allocation of Resources Without Limits or Throttling
Allocation of Resources Without Limits or Throttling represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.