honojs Hono up to 4.12.33 CORS Middleware cors redos

Summaryinfo

A vulnerability, which was classified as problematic, has been found in honojs Hono up to 4.12.33. This vulnerability affects the function cors of the component CORS Middleware. This manipulation causes redos. This vulnerability is registered as CVE-2026-69207. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in honojs Hono up to 4.12.33. It has been declared as problematic. Affected by this vulnerability is the function cors of the component CORS Middleware. The manipulation with an unknown input leads to a redos vulnerability. The CWE definition for the vulnerability is CWE-1333. The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles. As an impact it is known to affect availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-69207 since 08/03/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1449.003 according to MITRE ATT&CK.

Upgrading to version 4.12.34 eliminates this vulnerability.

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Productinfo

Vendor

• honojs

Name

• Hono

Version

• 4.12.0
• 4.12.1
• 4.12.2
• 4.12.3
• 4.12.4
• 4.12.5
• 4.12.6
• 4.12.7
• 4.12.8
• 4.12.9
• 4.12.10
• 4.12.11
• 4.12.12
• 4.12.13
• 4.12.14
• 4.12.15
• 4.12.16
• 4.12.17
• 4.12.18
• 4.12.19
• 4.12.20
• 4.12.21
• 4.12.22
• 4.12.23
• 4.12.24
• 4.12.25
• 4.12.26
• 4.12.27
• 4.12.28
• 4.12.29
• 4.12.30
• 4.12.31
• 4.12.32
• 4.12.33

Website

• Product: https://github.com/honojs/hono/

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