CVE-2026-27700: honojs hono · Insufficient Verification of Data Authenticity
Affects honojs honoSource CVE Database V5
Not known to be exploited · CVSS 8.2 High : upgrade to 4.12.2 soon.
Data as of 30 Oct 2026, 06:59 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 19% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 4.12.2
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 25 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade honojs hono to 4.12.2.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| honojshono | Affected
| Fixed in
|
AI-suggested
Organizations should immediately upgrade the honojs framework to version 4.12.2 or later, which contains the patch correcting the IP extraction logic. Until the upgrade can be applied, as a temporary mitigation, organizations can implement additional validation on the X-Forwarded-For header by inspecting the last IP address in the list rather than the first, or by configuring the ALB to use a different header for the real client IP if possible. Additionally, consider implementing defense-in-depth by combining IP-based restrictions with other authentication and authorization mechanisms, such as token-based authentication or mutual TLS, to reduce reliance on IP filtering alone. Monitoring and logging of suspicious IP addresses and unusual access patterns can help detect exploitation attempts. Network-level controls, such as AWS WAF rules, can also be configured to block suspicious requests with malformed or suspicious X-Forwarded-For headers. Finally, educate developers and security teams about the risks of trusting client-supplied headers without proper validation, especially in cloud load balancer environments.
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.