Medium severity · published Aug 31, 2026
CVE-2026-81888
@hono/oauth-providers: OAuth state check fails open on omitted state, enabling login CSRF and forced account linking
5.4
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 9% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
HO
@hono/oauth-providers · honojs
< 0.8.6 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-81888
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-81888
github.com
https://github.com/honojs/middleware/commit/b37765f40b7bddb1d8fce39573b085222dea58c1
github.com
https://github.com/honojs/middleware/pull/2040
github.com
https://github.com/honojs/middleware/releases/tag/%40hono%2Foauth-providers%400.8.6
github.com
https://github.com/honojs/middleware/security/advisories/GHSA-fm3f-ch8h-qw8q