# CVE-2026-5423: Subscription Authentication Bypass via Unverified connectionParams.jwt

> Unauthenticated attackers can forge JWT claims in GraphQL subscriptions to bypass authentication and access restricted data.

- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 6 Aug 2026
- **Updated:** 6 Aug 2026
- **Also known as:** GHSA-fcpg-3fw5-vc65

## What is CVE-2026-5423?

CVE-2026-5423 is a high-severity authentication bypass vulnerability in neo4j graphql, published on 6 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

@neo4j/graphql library versions prior to 7.5.6 fail to verify the authenticity of a client-supplied, pre-decoded JWT object passed through GraphQL subscription connectionParams. As a result, any unauthenticated remote client that can open a GraphQL-over-WebSocket connection can forge arbitrary JWT claims (e.g. sub, roles) in connectionParams.jwt and have them accepted as authenticated identity for the purposes of @authentication and @subscriptionsAuthorization directive evaluation. This allows a fully unauthenticated attacker to receive subscription events that should be restricted to specific authenticated roles/users.
Upgrade the library to versions 7.5.6+ or 5.12.14+. v6 is end-of-life and will not receive a fix.

Weakness: CWE-302 (Authentication Bypass by Assumed-Immutable Data)

## Which versions are affected by CVE-2026-5423?


## How do I fix CVE-2026-5423?

No fix has been published for CVE-2026-5423 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-5423 being exploited?

There is no known exploitation of CVE-2026-5423 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5423 and fix it if it is affected.

What it is: CVE-2026-5423 is a high-severity authentication bypass vulnerability in neo4j graphql, published on 6 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-2026-5423 in the wild and no public exploit code.

Affected product: neo4j graphql. 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-2026-5423/ (Markdown: https://insights.sbomify.com/CVE-2026-5423/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5423
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5423
- OSV: https://osv.dev/vulnerability/CVE-2026-5423

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5423/
Summaries are generated and may contain mistakes; the official description above is the record.