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.)

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Fixes

Solution

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Workaround

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History

Thu, 16 Jul 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 16 Jul 2026 18:45:00 +0000

Type Values Removed Values Added
Description 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.)
First Time appeared Cyrusimap
Cyrusimap cyrus Imap
Weaknesses CWE-340
CPEs cpe:2.3:a:cyrusimap:cyrus_imap:*:*:*:*:*:*:*:*
Vendors & Products Cyrusimap
Cyrusimap cyrus Imap
References
Metrics cvssV3_1

{'score': 4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:N'}


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cve-icon MITRE

Status: PUBLISHED

Assigner: mitre

Published:

Updated: 2026-07-16T18:54:53.528Z

Reserved: 2026-05-18T00:00:00.000Z

Link: CVE-2026-47085

cve-icon Vulnrichment

Updated: 2026-07-16T18:54:47.753Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-07-16T19:30:05Z

Weaknesses