How serious is CVE-2026-27700?

This vulnerability has a CVSS score of 7.5 out of 10, classified as HIGH severity. Proof-of-concept exploit code is publicly available, making this an active threat.

Is there exploit code available for CVE-2026-27700?

Yes, proof-of-concept exploit code for CVE-2026-27700 is publicly available on GitHub and security research platforms. This increases the risk of active exploitation.

Which products are affected by CVE-2026-27700?

CVE-2026-27700 affects hono hono. Check the full CVE details for specific version information.

How do I fix CVE-2026-27700?

To remediate CVE-2026-27700, check for security patches from hono. Apply all available updates and security patches. If no patch is available, implement recommended workarounds or security controls to mitigate the risk.

CVE-2026-27700

High

|7.5

Exploit Available

Plain English Summary

AI-powered analysis for quick understanding

An attacker can bypass IP-based access controls in Hono applications by manipulating the `X-Forwarded-For` header, allowing them to gain unauthorized access to restricted areas. This vulnerability occurs specifically when using the AWS Lambda adapter behind an Application Load Balancer in versions 4.12.0 and 4.12.1, and it has been fixed in version 4.12.2.

Technical Description

Hono is a Web application framework that provides support for any JavaScript runtime. In versions 4.12.0 and 4.12.1, 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. Version 4.12.2 patches the issue.

CVSS Vector Analysis

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

Confidentiality ImpactHigh

Integrity ImpactNone

Availability ImpactNone

ScopeUnchanged

Vector String

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

Exploit Resources

Search for proof-of-concept code and exploit modules

GitHub Search Exploit-DB Nuclei Templates Metasploit Vulners

Official References

NIST NVD

Est. Bounty

$2,053($1K-$5K)

Vendor Response

Grade APatched in 4 days

Quick Information

Published

Feb 25, 2026

about 1 month ago

Last Modified

Mar 2, 2026

about 1 month ago

Vendor

hono

Product

hono