Medium [CVE-2026-47086] Information disclosure via URLAUTH token bypass of Access Control Lists
This medium-severity Red Hat Linux advisory covers CVE-2026-47086 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7.
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Summary
An issue was discovered in cyrus-imapd in Cyrus IMAP through 3.12.2. GENURLAUTH-issued tokens can bypass ACLs.
Any authenticated user could mint a URLAUTH token (via the GENURLAUTH command) for any mailbox they could name, even without read access on it. This would allow reading mail from mailboxes despite having no granted permissions.
This allows bypassing Access Control Lists (ACLs), which are rules that control access to mailboxes. Consequently, an attacker could read mail from any mailbox, even without having been granted explicit read permissions.
This flaw in cyrus-imapd allows an authenticated attacker to bypass Access Control Lists (ACLs) by minting a URLAUTH token via the GENURLAUTH command. Red Hat severity: Moderate — CVSS 4.3 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N).
Weakness: CWE-639. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9.
Will not fix / out of support: Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7. Red Hat does not currently list a fixing RHSA for this CVE.
Affected products named by the advisory: Red Hat package: cyrus-imapd.
- 3.12.2
Official advisory · high-confidence parse· fetched 12 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 12 days ago·verify at source
Mitigation checklist
- To reduce the attack surface, restrict network access to the Cyrus IMAP server to only trusted clients and networks by configuring appropriate firewall rules. If the Cyrus IMAP service is not essential, consider disabling it. To disable the `cyrus-imapd` service, execute `sudo systemctl stop cyrus-imapd` and `sudo systemctl disable cyrus-imapd`. Disabling the service will prevent all mail access via IMAP and may require a system restart to fully take effect.
Official advisory · high-confidence parse· fetched 12 days ago·verify at source
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