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CVE Record

CVE-2026-42006: An attacker can cause uncontrolled memory usage with excessive bracing over IMAP.

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.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A remote attacker can send malformed IMAP input containing excessive opening braces, forcing the mail service to consume memory up to its configured limit. This can disrupt email availability without authentication or user interaction. The earlier CVE-2026-27857 fix did not close this alternate path.

Executive priority

Prioritize remediation for internet-facing or business-critical IMAP systems. Although no public exploitation is reported, unauthenticated remote availability impact and an incomplete previous fix justify prompt patching. Confirm exact affected versions through vendor guidance because the supplied version metadata is incomplete.

Technical view

CVE-2026-42006 is a network-reachable resource-exhaustion flaw affecting OX Dovecot Pro. Excessive opening braces bypass the incomplete closing-brace restriction from CVE-2026-27857. CVSS 3.1 is 7.5, reflecting unauthenticated, low-complexity denial of service with high availability impact but no stated confidentiality or integrity impact.

Likely exposure

Systems are most exposed when affected OX Dovecot Pro IMAP services are network-reachable. The supplied affected-version data lists placeholder values and does not establish precise vulnerable releases. Administrators must compare installed builds with the Open-Xchange advisory and applicable Red Hat errata.

Exploitation context

No publicly available exploits are known, and the CVE is not identified as a CISA KEV entry in the supplied bundle. Exploitation nevertheless requires no privileges or user interaction and can occur remotely over IMAP, making exposed services credible denial-of-service targets.

Researcher notes

The weakness maps to CWE-400 and CWE-770. The important distinction from CVE-2026-27857 is that closing braces were constrained while opening braces remained usable to evade the intended limit. The bundle states memory can grow to the configured ceiling; it does not establish code execution, data disclosure, or publicly available exploit tooling.

Mitigation direction

  • Install the fixed version identified by Open-Xchange or the applicable Red Hat erratum.
  • Until updated, configure a low, operationally tested vsz_limit for IMAP processes.
  • Restrict unnecessary public IMAP exposure using existing network access controls.
  • Monitor IMAP process memory and service restarts for abnormal resource consumption.

Validation and detection

  • Inventory OX Dovecot Pro and related Red Hat packages serving IMAP.
  • Compare installed package builds with the vendor advisory and applicable Red Hat errata.
  • Confirm IMAP processes have an appropriately low, tested vsz_limit.
  • Review monitoring data for unusual IMAP memory growth, crashes, or repeated restarts.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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 · low confidence lookup

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 lookup
cwe · low confidence lookup

CWE-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 lookup
cve · low confidence lookup

CVE-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
Vulnerability profileCVE Program record
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

Official CVE source material

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.

2CVSS vectors
5Timeline events
2ADP providers
16Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

2 official scores

We 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.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADP
4.3CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L2.81.4OX

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-42006Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPdovecot: Dovecot: Denial of Service via excessive IMAP bracing
other:Red Hat severity ratingcvssV3_1
  • 2026-05-12T14:02:01.841Z: Reported to Red Hat.
  • 2026-05-12T13:28:46.922Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Open-Xchange GmbHOX Dovecot Pro0, 0, 0unaffected
Weakness

CWE details

CWE-400CWE-770

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-400 · source CWE mapping

Uncontrolled Resource Consumption

Uncontrolled Resource Consumption represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-770 · source CWE mapping

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.

Open CWE intelligenceSame-CWE CVEs