# CVE-2026-73208: Auth bypass in OX Dovecot CE

> Attackers can authenticate using tokens with mismatched audience claims if scope claims are missing, bypassing authorization checks in Dovecot.

- **Severity:** High 7.4 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** ALPINE-CVE-2026-73208, AZL-98295, DEBIAN-CVE-2026-73208, GHSA-856w-5q8f-fq73, UBUNTU-CVE-2026-73208

## What is CVE-2026-73208?

CVE-2026-73208 is a high-severity authentication bypass vulnerability in Open-Xchange GmbH OX Dovecot CE, published on 28 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An attacker that holds a token intended for a different purpose can authenticate, because when an OAuth2 token response does not contain a scope claim, the audience claim is used in its place and checked against the configured required scopes. These are different concepts, and the audience claim does not describe what a token is allowed to do. A token that grants no relevant permissions can be accepted because its intended recipient value happens to match a configured scope name, granting access that should have been denied. It also hides an identity provider misconfiguration where scopes are not being issued at all. Ensure the identity provider issues a scope claim for all tokens used with Dovecot, and that configured scope names do not match audience values. Update to non-vulnerable version. No publicly available exploits are known.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-73208?


## How do I fix CVE-2026-73208?

Upgrade to a fixed version.

## Is CVE-2026-73208 being exploited?

There is no known exploitation of CVE-2026-73208 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-73208 and fix it if it is affected.

What it is: CVE-2026-73208 is a high-severity authentication bypass vulnerability in Open-Xchange GmbH OX Dovecot CE, published on 28 Aug 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-2026-73208 in the wild and no public exploit code.

Affected product: Open-Xchange GmbH OX Dovecot CE. 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-2026-73208/ (Markdown: https://insights.sbomify.com/CVE-2026-73208/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-73208
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-73208
- OSV: https://osv.dev/vulnerability/CVE-2026-73208

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-73208/
Summaries are generated and may contain mistakes; the official description above is the record.