# CVE-2026-47085: Auth bypass in Cyrus IMAP

> Attackers can forge URLAUTH tokens to read mailbox data if the obscure URLAUTH feature is enabled and folder names are known.

- **Severity:** Medium 4.0 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Jul 2026
- **Updated:** 16 Jul 2026
- **Also known as:** DEBIAN-CVE-2026-47085, GHSA-8jrh-wq6h-53c4, UBUNTU-CVE-2026-47085

## What is CVE-2026-47085?

CVE-2026-47085 is a medium-severity authentication bypass vulnerability in cyrusimap Cyrus IMAP, published on 16 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.)

Weakness: CWE-340 (Generation of Predictable Numbers or Identifiers)

## Which versions are affected by CVE-2026-47085?


## How do I fix CVE-2026-47085?

Apply the vendor's patch.

## Is CVE-2026-47085 being exploited?

There is no known exploitation of CVE-2026-47085 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-47085 and fix it if it is affected.

What it is: CVE-2026-47085 is a medium-severity authentication bypass vulnerability in cyrusimap Cyrus IMAP, published on 16 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-47085 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-2026-47085/ (Markdown: https://insights.sbomify.com/CVE-2026-47085/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-47085
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-47085
- OSV: https://osv.dev/vulnerability/CVE-2026-47085

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-47085/
Summaries are generated and may contain mistakes; the official description above is the record.