Bug 2501666

Summary: CVE-2026-47085 cyrus-imapd: Cyrus IMAP: Information disclosure via URLAUTH token forgery [fedora-all]
Product: [Fedora] Fedora Reporter: Ganesh <gnaik>
Component: cyrus-imapdAssignee: Martin Osvald 🛹 <mosvald>
Status: NEW --- QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: medium    
Version: rawhideCC: fhrdina, jorton, j, mosvald, pavel, zdohnal
Target Milestone: ---Keywords: Security, SecurityTracking
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Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["c43be8dd-a61f-491a-abee-87dd353ecd26"]}
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On:    
Bug Blocks: 2501446    

Description Ganesh 2026-07-17 03:52:27 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

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 no public clients use URLAUTH.)