# CVE-2026-61909: Missing authorization in Cyrus IMAP

> Authenticated users can bypass ACLs to read unshared calendar or address book entries via multiget requests in Cyrus IMAP.

- **Severity:** Low 3.5 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Sep 2026
- **Updated:** 14 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-61909, GHSA-q4vc-r364-vq8w, UBUNTU-CVE-2026-61909

## What is CVE-2026-61909?

CVE-2026-61909 is a low-severity missing authorization vulnerability in cyrusimap Cyrus IMAP, published on 9 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

An issue was discovered in Cyrus IMAP before 3.12.4. CalDAV/CardDAV multiget bypasses a per-href ACL. An authenticated DAV user with some shared access to another user's calendar or address book could read even unshared events or contacts by including the target hrefs in a calendar-multiget or addressbook-multiget REPORT.

Weakness: CWE-420 (Unprotected Alternate Channel)

## Which versions are affected by CVE-2026-61909?

It affects 1 product.


Products: Cyrus Imap.

## How do I fix CVE-2026-61909?

Upgrade to a fixed version.

## Is CVE-2026-61909 being exploited?

There is no known exploitation of CVE-2026-61909 in the wild and no public exploit code.

## Other vulnerabilities in cyrusimap Cyrus IMAP

- [CVE-2019-18928](https://insights.sbomify.com/CVE-2019-18928/): Auth bypass in n/a (critical 9.8)
- [CVE-2017-14230](https://insights.sbomify.com/CVE-2017-14230/): Information disclosure in n/a (critical 9.1)
- [CVE-2021-33582](https://insights.sbomify.com/CVE-2021-33582/): Denial of service in n/a (high 7.5)
- [CVE-2015-8076](https://insights.sbomify.com/CVE-2015-8076/): Information disclosure in n/a (high 7.5)
- [CVE-2015-8077](https://insights.sbomify.com/CVE-2015-8077/): Integer overflow in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-61909 and fix it if it is affected.

What it is: CVE-2026-61909 is a low-severity missing authorization vulnerability in cyrusimap Cyrus IMAP, published on 9 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-61909 in the wild and no public exploit code.

Affected product: cyrusimap Cyrus IMAP. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-61909/ (Markdown: https://insights.sbomify.com/CVE-2026-61909/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-61909
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-61909
- OSV: https://osv.dev/vulnerability/CVE-2026-61909

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-61909/
Summaries are generated and may contain mistakes; the official description above is the record.