# CVE-2026-92087: @fastify/auth vulnerable to Authorization Bypass via order-dependent evaluation of composed auth

> Attackers can bypass authorization checks in @fastify/auth by exploiting order-dependent evaluation in composed strategies, gaining unauthorized access.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Sep 2026
- **Updated:** 17 Sep 2026
- **Also known as:** GHSA-7h52-2rwr-m76r

## What is CVE-2026-92087?

CVE-2026-92087 is a high-severity authentication bypass vulnerability in @fastify/auth, published on 16 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

@fastify/auth is a Fastify plugin that composes multiple authentication and authorization strategies into a single route guard. In versions 5.0.0 through 5.1.0, when strategies are composed with the relation "or" option together with the run "all" option and one entry is a nested array acting as an AND group, the group is evaluated in an order-dependent way: an earlier failing check is silently dropped and the group's result becomes the outcome of its last check. As a result, a request that satisfies only the last member of an AND group, for example an attacker who holds a valid API key but is not an administrator, is authorized instead of rejected, and a related order-dependent bypass affects the mirror configuration where the top-level relation is "and" and a nested group uses "or". The issue is fixed in @fastify/auth 5.1.1, and users should upgrade to 5.1.1 or later. As a workaround, omit the run "all" option where it is not required, order each AND group so its stricter check is evaluated last, or replace nested AND groups with an explicit top-level "and" composition.

Weakness: CWE-697 (Incorrect Comparison), CWE-285 (Improper Authorization)

## Which versions are affected by CVE-2026-92087?


## How do I fix CVE-2026-92087?

No fix has been published for CVE-2026-92087 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-92087 being exploited?

There is no known exploitation of CVE-2026-92087 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-92087 and fix it if it is affected.

What it is: CVE-2026-92087 is a high-severity authentication bypass vulnerability in @fastify/auth, published on 16 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-92087 in the wild and no public exploit code.

Affected product: @fastify/auth. 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-2026-92087/ (Markdown: https://insights.sbomify.com/CVE-2026-92087/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-92087
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-92087
- OSV: https://osv.dev/vulnerability/CVE-2026-92087

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-92087/
Summaries are generated and may contain mistakes; the official description above is the record.