GHSA-xh87-mx6m-69f3
Hono is Vulnerable to Authentication Bypass by IP Spoofing in AWS Lambda ALB conninfo
At a glance
- Published
- Updated
- CVE
- CVE-2026-27700
- CVSS_V3
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
Description
## Summary When using the AWS Lambda adapter (`hono/aws-lambda`) behind an Application Load Balancer (ALB), the `getConnInfo()` function incorrectly selected the first value from the `X-Forwarded-For` header. Because AWS ALB appends the real client IP address to the end of the `X-Forwarded-For` header, the first value can be attacker-controlled. This could allow IP-based access control mechanisms (such as the `ipRestriction` middleware) to be bypassed. ## Details In ALB environments, AWS appends the actual client IP address to the end of any existing `X-Forwarded-For` header value. However, the previous implementation of `getConnInfo()` extracted the leftmost IP address: ```ts address = xff.split(',')[0].trim() ``` If a client sent: ``` X-Forwarded-For: <spoofed-ip> ``` ALB would forward: ``` X-Forwarded-For: <spoofed-ip>, <real-client-ip> ``` Since the implementation selected the first value, the spoofed IP address was trusted. This affected applications using: ```ts ipRestriction(getConnInfo, { allowList: [...] }) ``` or any custom middleware relying on `getConnInfo(c).remote.address` for authorization decisions. The issue only affects deployments using the AWS Lambda adapter behind an ALB. API Gateway (v1/v2) and Lambda Function URLs are not affected, as they use AWS-provided source IP values from `requestContext`. ## Impact An unauthenticated remote attacker could bypass IP-based access restrictions by supplying a crafted `X-Forwarded-For` header. This may allow access to resources that were intended to be restricted by IP address. Only applications deployed behind an ALB and relying on `getConnInfo()` for IP-based authorization are affected.
Affected packages
| Package | Versions |
|---|---|
| npm · hono | introduced 4.12.0, fixed 4.12.2 |
References
- https://github.com/honojs/hono/security/advisories/GHSA-xh87-mx6m-69f3 WEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-27700 ADVISORY
- https://github.com/honojs/hono/commit/41adbf56e252c04611f8972364ac0887ae07a4c7 WEB
- https://github.com/honojs/hono PACKAGE
- https://github.com/honojs/hono/releases/tag/v4.12.2 WEB
Sources
| Source | Licence |
|---|---|
| OSV.dev | CC-BY 4.0 — GitHub Advisory Database |