CVE-2026-81888 @hono/oauth-providers: OAuth state check fails open on omitted state, enabling login CSRF and forced account linking
Attackers can bypass OAuth state validation to perform login CSRF and force account linking in applications using Hono OAuth providers.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-81888?
CVE-2026-81888 is a medium-severity vulnerability in honojs @hono/oauth-providers, published on 31 Aug 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
@hono/oauth-providers is Authentication middleware for Hono. Prior to version 0.8.6, the built-in social login providers accept an OAuth callback even when the `state` value is absent on both sides, so the anti-CSRF check passes for a callback that never came from a genuine login attempt. This defeats the `state`-based CSRF protection under default usage. Version 0.8.6 has a patch.
Which versions are affected by CVE-2026-81888?
2 open source packages ship an affected version, including @hono/oauth-providers.
| Package | Affected | Fixed in |
|---|---|---|
@hono/oauth-providers npm | All versions | 0.8.6 |
@hono/oauth-providers npm | All versions | 0.8.6 |
How do I fix CVE-2026-81888?
Upgrade @hono/oauth-providers to 0.8.6 or later.
Is CVE-2026-81888 being exploited?
There is no known exploitation of CVE-2026-81888 in the wild and no public exploit code.
Sources
Also known as GHSA-fm3f-ch8h-qw8q.