CVE-2026-69207: honojs hono

Vulnerability summary

CVE-2026-69207 is a medium (CVSS 5.3) vulnerability in honojs hono. EPSS estimates a 0.61% chance of exploitation in the next 30 days, higher than 48.4% of scored vulnerabilities.

Timeline

1. 07-08-2026
   PublishedVulnerability first disclosed.
2. 10-08-2026
   Last modifiedVulnerability information updated.

Description

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.34, the built-in CORS middleware, hono/cors, is vulnerable to a regular expression denial of service (ReDoS). During a preflight OPTIONS request, the middleware parses the attacker-controlled Access-Control-Request-Headers header using a whitespace-tolerant regular expression whose backtracking makes its running time quadratic in the input length. Because the header value is bounded only by the deployment's maximum HTTP header size, a single preflight carrying a long run of whitespace can consume seconds of CPU and block request processing. On runtimes that share one execution thread across requests, this stalls concurrent requests as well, and repeated requests can render the service unresponsive. This affects the default configuration, since the vulnerable path is reached whenever cors() is used with an unset or empty allowHeaders. Applications that set a non-empty allowHeaders are not affected. This issue is fixed in version 4.12.34.

• CWE-1333Inefficient Regular Expression ComplexityThe product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.