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

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

• dovecot dovecotbefore 2.4.4
• open-xchange dovecotbefore 3.1.5

Versions reported by the vendor

Affected version ranges reported by the assigning authority (OX). Independent of NVD's CPE analysis and usually ahead of it.

• Open-Xchange GmbH OX Dovecot Pro

  • up to and including 3.0.5affected · semver
  • up to and including 3.1.4affected · semver
  • up to and including 2.4.3affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Other highest-scoring records for the same primary product.

• CVE-2019-11500In Dovecot before 2.2.36.4 and 2.3.x before 2.3.7.2 (and Pigeonhole before 0.5.7.2), protocol processing can fail for quoted strings.
  58Plan
• CVE-2020-7046lib-smtp in submission-login and lmtp in Dovecot 2.3.9 before 2.3.9.3 mishandles truncated UTF-8 data in command parameters, as demonstrated
  45Plan
• CVE-2016-8652The auth component in Dovecot before 2.2.27, when auth-policy is configured, allows a remote attackers to cause a denial of service (crash)
  37Monitor

Published before and after this one in the same product

• ← EarlierCVE-2026-33603May 12, 2026 · Attacker can use a specially crafted base64 exchange between Dovecot and Client to fake SCRAM TLS channel binding.
  21Monitor
• ← EarlierCVE-2026-40016May 12, 2026 · Attacker can upload a malicious Sieve script over ManageSieve service (or locally) to bypass configured CPU time limits for Sieve up to 130
  26Monitor
• ← EarlierCVE-2026-40020May 12, 2026 · Attacker can use the IMAP SETACL command to inject the anyone permission to user's dovecot-acl file even if imap_acl_allow_anyone=no.
  17Monitor

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

1function expand(node) {2  return node.children.map(expand);3}

1const MAX_DEPTH = 32;2function expand(node, depth = 0) {3  if (depth > MAX_DEPTH) throw new Error("too deep");4  return node.children.map((c) => expand(c, depth + 1));5}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.