What’s Vulnerable › Vulnerabilities

CVE-2026-81888: @hono/oauth-providers: OAuth state check fails open on omitted state, enabling login CSRF and forced account linking

• Severity: medium (CVSS 5.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-31 · updated 2026-09-09
• Weakness: CWE-352

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.

Affected products

• honojs @hono/oauth-providers: before 0.8.6

References

• https://github.com/honojs/middleware/commit/b37765f40b7bddb1d8fce39573b085222dea58c1
• https://github.com/honojs/middleware/pull/2040
• https://github.com/honojs/middleware/releases/tag/%40hono%2Foauth-providers%400.8.6
• https://github.com/honojs/middleware/security/advisories/GHSA-fm3f-ch8h-qw8q

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