CVE-2026-47085
CVE-2026-47085 is a medium-severity vulnerability with a CVSS 3.x base score of 4.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-340.
Key facts
- Severity: Medium (CVSS 3.x base score 4.0)
- EPSS exploit prediction: 0% (10th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-340
- Published:
- Last modified:
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.)
Frequently asked questions
- What is CVE-2026-47085?
- 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.)
- How severe is CVE-2026-47085?
- CVE-2026-47085 has a CVSS 3.x base score of 4.0, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
- Is CVE-2026-47085 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (10th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-47085?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- When was CVE-2026-47085 published?
- CVE-2026-47085 was published on 2026-07-16 and last updated on 2026-07-17.
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
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