# CVE-2026-104056: CVE-2026-104056

> Attackers can poison cached discovery metadata to redirect authentication endpoints, bypassing origin validation in Authlib.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 1 Oct 2026
- **Updated:** 5 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-104056, GHSA-8wx9-759m-hfm8, UBUNTU-CVE-2026-104056

## What is CVE-2026-104056?

CVE-2026-104056 is a critical vulnerability in Authlib, published on 1 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Authlib version 1.7.2 and below contains a vulnerability where discovery JSON metadata is cached without validation or issuer-origin binding. This allows a poisoned discovery response to replace all endpoint values with attacker-controlled values rather than endpoint URLs that share the origin of the configured server metadata URL.

Weakness: CWE-829 (Inclusion of Functionality from Untrusted Control Sphere), CWE-346 (Origin Validation Error), CWE-345 (Insufficient Verification of Data Authenticity)

## Which versions are affected by CVE-2026-104056?


## How do I fix CVE-2026-104056?

No fix has been published for CVE-2026-104056 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-104056 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-104056 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-104056 and fix it if it is affected.

What it is: CVE-2026-104056 is a critical vulnerability in Authlib, published on 1 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-104056 exists.

Affected product: Authlib. 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-2026-104056/ (Markdown: https://insights.sbomify.com/CVE-2026-104056/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-104056
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-104056
- OSV: https://osv.dev/vulnerability/CVE-2026-104056

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-104056/
Summaries are generated and may contain mistakes; the official description above is the record.