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An issue was discovered in cyrus-imapd in Cyrus IMAP through 3.12.2. URLAUTH token forgery can occur via a missing mboxkey. If an attacker knew a folder name on the victim's account for which the vic…

Medium CVSS 4.0
CVECVE-2026-47085
First seen2026-07-17 19:16 UTC
Disclosed2026-07-16 19:16 UTC
Last updated2026-07-17 19:16 UTC
Channel statusauto

Summary

An issue was discovered in cyrus-imapd in Cyrus IMAP through 3.12.2. URLAUTH token forgery can occur via a missing mboxkey. If an attacker knew a folder name on the victim's account for which the victim had never issued an auth URL, they could forge a working URLAUTH token by computing an HMAC-SHA1 value with a predictable key, giving them read access to the mailbox. (URLAUTH is an obscure feature, meaning that the odds of any user actually being susceptible to this attack are very low. Perhaps…

In-depth triage · Auto channel

No in-depth report has been generated yet (DR-003 v2 AI pipeline is under construction).

Lint boundary warnings (2)

The following non-blocking warnings were raised during the lint phase of this triage (e.g. reference URLs not yet on the allowlist). They do not affect entry usability and are disclosed for transparency (see DR-002).

  • REF_URL_NOT_ALLOWLISTED url not in allowlist: https://www.cyrusimap.org/3.12/imap/download/release-notes/3.12/x/3.12.3.html
  • REF_URL_NOT_ALLOWLISTED url not in allowlist: https://www.cyrusimap.org/imap/download/release-notes/index.html

Sources

  • NVD DATABASE

Original Links

Timeline

  1. nvd_ingest NVD