How severe is CVE-2026-61911?

CVE-2026-61911 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2026-61911 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-61911?

CVE-2026-61911 affects Cyrus Imap. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-61911?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-61911 published?

CVE-2026-61911 was published on 2026-09-09 and last updated on 2026-09-16.

CVE-2026-61911

CVE-2026-61911 is a medium-severity vulnerability in Cyrus Imap with a CVSS 3.x base score of 4.3. 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-497.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
EPSS exploit prediction: 0% (11th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-497
Affected product: Cyrus Imap
Published: 2026-09-09
Last modified: 2026-09-16

Description

An issue was discovered in Cyrus IMAP before 3.12.4. There is a Sieve mailbox existence oracle. An authenticated user could install a Sieve script that probed whether another user's private mailbox existed, or read the value of shared mailbox annotations, by observing which fileinto branch fired during LMTP delivery.

Frequently asked questions

What is CVE-2026-61911?: An issue was discovered in Cyrus IMAP before 3.12.4. There is a Sieve mailbox existence oracle. An authenticated user could install a Sieve script that probed whether another user's private mailbox existed, or read the value of shared mailbox annotations, by observing which fileinto branch fired during LMTP delivery.
How severe is CVE-2026-61911?: CVE-2026-61911 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2026-61911 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-61911?: CVE-2026-61911 affects Cyrus Imap. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-61911?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-61911 published?: CVE-2026-61911 was published on 2026-09-09 and last updated on 2026-09-16.

References

Affected products (1)

cpe:2.3:a:cyrus:imap:*:*:*:*:*:*:*:*

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