high7.4
CVE-2026-114616
Authlib accepts an empty HMAC key, allowing JWS/JWT signature forgery (HS256/HS384/HS512)
Impact
Authlib is a Python library which builds OAuth and OpenID Connect servers. Prior to 1.9.1, Authlib's OctKey.import_key() and HMAC signing and verification path accept zero-length key material. If an application's secret lookup can return an empty string or empty bytes, a remote attacker can compute the deterministic HS256, HS384, or HS512 signature for arbitrary token claims and have Authlib treat the token as authentic. This issue is fixed in version 1.9.1.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | Authlib | < 1.9.1 | 1.9.1 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Authlib | Authlib | before 1.9.1 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-8m4g-j4wp-wgcg
- https://github.com/authlib/authlib/security/advisories/GHSA-8m4g-j4wp-wgcg
- https://nvd.nist.gov/vuln/detail/CVE-2026-114616
- https://github.com/authlib/authlib/commit/4ff30db442c70e29486e1982cb0ad37c037f5f4b
- https://github.com/authlib/authlib/releases/tag/v1.9.1