GHSA-xgm2-5f3f-mvvc CVE-2026-59897
Hono: API Gateway v1 adapter can drop a distinct repeated request header value during de-duplication
- Severity
- 4.8 / 10
- Medium · CVSS 3.1
- Exploit chance (EPSS)
- 0.18%
- Chance of exploitation in the next 30 days. Higher than 7.54% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-348 Use of Less Trusted Source
- Fix
4.12.27- Upgrade hono to this version or later
Description
Summary
The AWS API Gateway v1 adapter can drop a distinct repeated request header value. When a header appears multiple times, the adapter de-duplicates values using a substring comparison instead of an exact match, so a value that is a substring of another value of the same header is omitted (for example, 203.0.113.1 is dropped when another value is 203.0.113.10).
Details
A repeated request header carries an ordered list of values. Middleware or application logic that depends on the complete list — such as IP restriction that walks the X-Forwarded-For chain, rate limiting, audit logging, or proxy-chain validation — can therefore receive incomplete data that differs from what the client actually sent.
This issue arises on deployments using the AWS API Gateway v1 adapter (the same pattern also affects the VPC Lattice adapter), for requests that contain the same header more than once.
Impact
An attacker can craft repeated header values so that one value is omitted before the application sees the request. Where a security or routing decision relies on the full chain, this can alter that decision.
This affects applications deployed through Hono's AWS API Gateway v1 (or VPC Lattice) adapter that rely on the complete set of repeated request header values.
Affected versions
npm
| Package | Vulnerable | Fixed in |
|---|---|---|
| hono | >= 4.3.3, < 4.12.27 |
4.12.27 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
hono npm → 4.12.27
- npm
npm install hono@4.12.27- yarn
yarn add hono@4.12.27- pnpm
pnpm add hono@4.12.27
Severity breakdown
CVSS 3.1 4.8
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
Weakness
CWE-348: Use of Less Trusted Source
The product has two different sources of the same data or information, but it uses the source that has less support for verification, is less trusted, or is less resistant to attack.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-5r4p-p66f-jhc7 Hono: `serveStatic` decodes the request path a second time, leading to bypass of middleware on static paths | Medium | Also affects hono |
| GHSA-hxh3-vqpv-xpqv hono/jsx renders plain strings unescaped in boundary components, leading to XSS | Low | Also affects hono |
| GHSA-gqvv-2mrq-wpjv Hono: Incomplete fix for CVE-2026-39408: `toSSG()` still writes files outside the output directory | Medium | Also affects hono |
| GHSA-g6gw-c38x-mqfc Hono: Unbounded dot-notation nesting in `parseBody()` can cause memory exhaustion | Medium | Also affects hono |
| GHSA-crvj-82cr-hjcx Hono: Query parser reads parameters after the URL fragment, causing cache-key and proxy interpretation differentials | Medium | Also affects hono |
| GHSA-f23p-vx2j-j53r Hono: `memo()` retains SSR output across requests, leading to cross-user data disclosure | Medium | Also affects hono |
| GHSA-79qm-7rj5-m7r9 Hono: Proxy Helper does not remove response headers listed in the `Connection` header | Low | Also affects hono |
| GHSA-54fx-42gc-7vw4 Hono: Algorithmic Complexity DoS in Language Middleware | Medium | Also affects hono |
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