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Vulnerabilities

Vulnerability · CVE-2026-27700

Hono is a Web application framework that provides support for any JavaScript runtime.

Published Feb 25, 2026 · catalog updated Jun 17, 2026 · Hono is a Web

Check if you run it

No confirmed exploitation is on record for CVE-2026-27700. EPSS is 0.35%. Act only if a listed version of Hono is a Web is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Hono is a Web).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.35%
Remediation
Advisory link
Affected products
cpe hono/hono

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 ( ) behind an Application Load Balancer (ALB), the function incorrectly selected the first value from the header. Because AWS ALB appends the real client IP address to the end of the header, the first value can be attacker-controlled. This could allow IP-based access control mechanisms (such as the middleware) to be bypassed. Version 4.12.2 patches the issue.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe hono/honoversion unspecified

How to fix CVE-2026-27700

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-27700. EPSS is 0.35%. Act only if a listed version of Hono is a Web is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-290: Authentication Bypass by Spoofing; CWE-345: Insufficient Verification of Data Authenticity. EPSS 0.35%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 25, 2026 · NIST NVD

    Detected

    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 ( ) behind an Application Load Balancer (ALB), the function incorrectly selected the first value from the header. Because AWS ALB appends the real client IP address to the end of the header, the first value can be attacker-controlled. This could all

  2. Jun 17, 2026 · NIST NVD

    Updated

    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 ( ) behind an Application Load Balancer (ALB), the function incorrectly selected the first value from the header. Because AWS ALB appends the real client IP address to the end of the header, the first value can be attacker-controlled. This could all

Sources

  • CVE.orgVulnerability recordCVE-2026-27700

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-27700

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-2026-27700

    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 ( ) behind an Application Load Balancer (ALB), the function incorrectly selected the first value

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.