# CVE-2026-114617: Authlib: ID token can disable its own nonce validation via the nonce_supported claim


- **Severity:** Medium 4.2 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 22 Oct 2026
- **Updated:** 23 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-114617, ECHO-1fc4-2a5e-a20a, GHSA-c5mf-xmp2-59rc, MINI-5pfm-5j5p-mc5r, UBUNTU-CVE-2026-114617

## What is CVE-2026-114617?

CVE-2026-114617 is a medium-severity vulnerability in authlib, published on 22 Oct 2026. 

### Official description

Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.0, OpenIDMixin.parse_id_token() reads the nonce_supported decision from the untrusted ID token being validated and sets the expected nonce to null when that claim is the JSON boolean false. In implicit and hybrid relying parties, or applications that directly accept externally supplied ID tokens, an attacker with a captured validly signed token can bypass the nonce-to-session binding and replay the victim's token into an attacker-controlled session. Plain authorization code flow is not affected, and the token must still pass signature, issuer, and audience validation. OpenIDMixin.parse_id_token() trusts nonce_supported in both authlib/integrations/base_client/sync_openid.py and authlib/integrations/base_client/async_openid.py to disable the expected nonce. This issue is fixed in version 1.9.0.

Weakness: CWE-807 (Reliance on Untrusted Inputs in a Security Decision), CWE-294 (Authentication Bypass by Capture-replay)

## Which versions are affected by CVE-2026-114617?

2 open source packages ship an affected version, including authlib. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `authlib` | PyPI | All versions | 1.9.0 |
| `authlib` | PyPI | All versions | 1.9.0 |

Products: Authlib Authlib.

## How do I fix CVE-2026-114617?

Upgrade authlib to 1.9.0 or later.

## Is CVE-2026-114617 being exploited?

There is no known exploitation of CVE-2026-114617 in the wild and no public exploit code.

## Other vulnerabilities in authlib

- [CVE-2026-27962](https://insights.sbomify.com/CVE-2026-27962/): Authlib JWS JWK Header Injection: Signature Verification Bypass (critical 9.1)
- [CVE-2026-28490](https://insights.sbomify.com/CVE-2026-28490/): Authlib Vulnerable to JWE RSA1_5 Bleichenbacher Padding Oracle (high 8.3)
- [CVE-2026-28498](https://insights.sbomify.com/CVE-2026-28498/): Authlib: Fail-Open Cryptographic Verification in OIDC Hash Binding (high 8.2)
- [CVE-2026-28802](https://insights.sbomify.com/CVE-2026-28802/): Authlib: Setting `alg: none` and a blank signature appears to bypass signature verification (high 7.7)
- [CVE-2025-61920](https://insights.sbomify.com/CVE-2025-61920/): Authlib is vulnerable to Denial of Service via Oversized JOSE Segments (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-114617 and fix it if it is affected.

What it is: CVE-2026-114617 is a medium-severity vulnerability in authlib, published on 22 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-114617 in the wild and no public exploit code.

Affected packages and fixed versions:
- authlib (PyPI): affected all versions; fixed in 1.9.0
- authlib (PyPI): affected all versions; fixed in 1.9.0

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-2026-114617/ (Markdown: https://insights.sbomify.com/CVE-2026-114617/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-114617
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-114617
- OSV: https://osv.dev/vulnerability/CVE-2026-114617

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-114617/
Summaries are generated and may contain mistakes; the official description above is the record.