Hono: ReDoS in CORS middleware via Access-Control-Request-Headers

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-69207
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-07 21:17:29 UTC
Updated2026-08-07 21:17:29 UTC
DescriptionHono 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.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Problem Types: CWE-1333 | CWE-1333 CWE-1333: Inefficient Regular Expression Complexity

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1CNADECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Honojs Hono affected < 4.12.34 Not specified

References

ReferenceSourceLinkTags
github.com/honojs/hono/commit/93fc250d8b4df58ea542cb945171de8013d5e6d5 [email protected] github.com
github.com/honojs/hono/security/advisories/GHSA-8j4g-w8fx-2239 [email protected] github.com
github.com/honojs/hono/releases/tag/v4.12.34 [email protected] github.com
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