# CVE-2026-52723: ePA 3.x Integration: VAU Server Authentication Bypass via Circular Certificate Trust

> A network attacker can bypass VAU server authentication via circular certificate trust to intercept and modify encrypted medical data traffic.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/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:** No
- **Published:** 18 Aug 2026
- **Updated:** 18 Aug 2026
- **Also known as:** GHSA-q2jw-6c4w-86jc

## What is CVE-2026-52723?

CVE-2026-52723 is a critical authentication bypass vulnerability in fbeta-GmbH ePA3-Service-OpenSource, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

ePA 3.x Integration implements the authorization workflow and writes Medical Information Objects to Germany's electronic patient record. Prior to 1.3.0, ePA 3.x Integration performs VAU server certificate validation in app/vau/VAUProtokoll.py without anchoring the signed_vau_server_pub_keys and AUT_VAU_CertData certificate path to independent trusted material. A network-positioned attacker between the DiGA backend and the ePA system can intercept the VAU handshake, supply attacker-controlled certificate and key material, and satisfy the circular trust relationship. Because TLS certificate verification is also disabled in affected versions, no independent server-authentication layer prevents the attack. The attacker can impersonate the VAU server, control the negotiated session keys, and read or modify all encrypted VAU traffic. This issue is fixed in version 1.3.0.

Weakness: CWE-295 (Improper Certificate Validation)

## Which versions are affected by CVE-2026-52723?


## How do I fix CVE-2026-52723?

No fix has been published for CVE-2026-52723 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-52723 being exploited?

There is no known exploitation of CVE-2026-52723 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-52723 and fix it if it is affected.

What it is: CVE-2026-52723 is a critical authentication bypass vulnerability in fbeta-GmbH ePA3-Service-OpenSource, published on 18 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-2026-52723 in the wild and no public exploit code.

Affected product: fbeta-GmbH ePA3-Service-OpenSource. 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-2026-52723/ (Markdown: https://insights.sbomify.com/CVE-2026-52723/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-52723
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-52723
- OSV: https://osv.dev/vulnerability/CVE-2026-52723

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-52723/
Summaries are generated and may contain mistakes; the official description above is the record.