How severe is GHSA-xh87-mx6m-69f3?

GHSA-xh87-mx6m-69f3 has a CVSS score of 8.2/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-xh87-mx6m-69f3?

GHSA-xh87-mx6m-69f3 affects the following packages: hono (npm). Ecosystems affected: npm.

How do I fix GHSA-xh87-mx6m-69f3?

Update hono to 4.12.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xh87-mx6m-69f3 is resolved across your whole dependency graph.

How do I detect GHSA-xh87-mx6m-69f3 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hono. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-xh87-mx6m-69f3 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-xh87-mx6m-69f3?

O3 pinpoints whether GHSA-xh87-mx6m-69f3 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-xh87-mx6m-69f3 actively exploited in the wild?

No public exploit code has been indexed for GHSA-xh87-mx6m-69f3 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-xh87-mx6m-69f3?

GHSA-xh87-mx6m-69f3 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 15th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-xh87-mx6m-69f3?

GHSA-xh87-mx6m-69f3 is classified as CWE-290 (CWE-290), CWE-345 (CWE-345). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-xh87-mx6m-69f3 published, and has it been updated?

GHSA-xh87-mx6m-69f3 was published on February 25, 2026 and was last updated on February 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

GHSA-xh87-mx6m-69f3

HIGH

Hono is Vulnerable to Authentication Bypass by IP Spoofing in AWS Lambda ALB conninfo

Also known asCVE-2026-27700

Published

Feb 25, 2026

Updated

Feb 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk15th percentile+0.24%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.

hononpm

50.0Mdownloads / week

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:

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:

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

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`hono`	≥ 4.12.0&&< 4.12.2	4.12.2

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hono. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update hono to 4.12.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xh87-mx6m-69f3 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-xh87-mx6m-69f3 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-xh87-mx6m-69f3. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## 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. Howeve

O3 Security · Impact-Aware SCA

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