Description
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 products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| authlib | authlib | < 1.9.1 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | python-authlib | 1.9.1-1 | — |
| Debian 13 | python-authlib | No fix yet | — |
| Debian 12 | python-authlib | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | python-authlib | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 26.04 LTS | python-authlib | No fix yet | — |
| Ubuntu Pro 24.04 LTS | python-authlib | No fix yet | — |
| Ubuntu Pro 22.04 LTS | python-authlib | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python-Authlib | 1.9.1-1.1 | openSUSE-SU-2026:12390-1 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | open-webui | 0.12.3-r12 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | authlib | < 1.9.1 | 1.9.1 | GHSA-8m4g-j4wp-wgcg |
Advisories 1
- openSUSE-SU-2026:12390-1 python313-Authlib-1.9.1-1.1 on GA media SUSE / openSUSE Security Updates · Nov 3, 2026