Cache-policy manipulation via reflected request Vary header
Published Jun 30, 2026 · Updated Jun 30, 2026
Header injection in Hono CORS middleware before 4.10.2 allows remote attackers to alter shared-cache behavior via crafted HTTP requests. When origin is not configured as "*", src/middleware/cors/index.ts reads Vary from the request and writes that attacker-controlled value to the response. The effect requires a shared cache or proxy that relies on Vary; default configurations have no direct confidentiality, integrity, or availability impact.
Summary
What happened
Header injection in Hono CORS middleware before 4.10.2 allows remote attackers to alter shared-cache behavior via crafted HTTP requests. When origin is not configured as "*", src/middleware/cors/index.ts reads Vary from the request and writes that attacker-controlled value to the response. The effect requires a shared cache or proxy that relies on Vary; default configurations have no direct confidentiality, integrity, or availability impact.
The record
- CVE
- CVE-2025-71381
- Published
- Jun 30, 2026
- Updated
- Jun 30, 2026
- Vendor
- Hono
- Product
- Hono
- Classifications
- CWE-113
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 30, 2026CVE publishedPublication date reported by the CVE source.
- Jun 30, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=0 <4.10.2
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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