CVE-2026-47086: Auth Bypass (CVSS 3.5)

Description

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.

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CVSS v3.1 Score

3.5

LOW

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N

EPSS — Exploit Prediction

0.0017

Probability of exploitation

0.07%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-863 Incorrect Authorization

References

Other References

https://www.cyrusimap.org/3.12/imap/download/release-notes/3.12/x/3.12.3.html https://www.cyrusimap.org/imap/download/release-notes/index.html

Frequently Asked Questions

What is CVE-2026-47086? +

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. It has a CVSS v3.1 base score of 3.5 (LOW).

How severe is CVE-2026-47086? +

CVE-2026-47086 has a CVSS v3.1 score of 3.5 out of 10, rated LOW. This is a low-severity vulnerability with limited impact. The EPSS score is 0.0017, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-47086? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-47086