CVE-2026-59897: Hono is a Web application framework that provides support for any JavaScript runtime

Q: How do I fix CVE-2026-59897?

hono: upgrade to 4.12.27. Exact commands for each OS are on this page.

Q: Is CVE-2026-59897 being exploited?

CVE-2026-59897 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-59897 affect?

CVE-2026-59897 affects hono. Severity is medium (CVSS 4.8). Hono is a Web application framework that provides support for any JavaScript runtime. From 4.3.3 before 4.12.27, the AWS API Gateway v1 adapter can drop a distinct repeated request header value because it de-duplicates values using a substr

Q: How urgent is CVE-2026-59897?

Priority 24/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 4.8REMOTEUPGRADE

CVE-2026-59897 is a medium-severity flaw (CVSS 4.8) affecting hono. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Hono is a Web application framework that provides support for any JavaScript runtime. From 4.3.3 before 4.12.27, the AWS API Gateway v1 adapter can drop a distinct repeated request header value because it de-duplicates values using a substring comparison instead of an exact match, so middleware or application logic that depends on the complete X-Forwarded-For chain, rate limiting, audit logging, or proxy-chain validation can receive incomplete da

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	4.8 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 93%)
CISA exploited list	No
Weakness	CWE-348
Published	2026-07-08
Last modified	2026-10-25

Publisher (CNA): GitHub, Inc. · Vendor: hono

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-08 17:17 UTCPublished CVE record published
2026-10-25 17:10 UTCUpdated Record last modified

hono hono UPGRADE

Affected: >= 4.3.3 and < 4.12.27

Fixed in: 4.12.27

Safe to downgrade to: a release before 4.3.3

1. Check installed version

npm ls hono

2. UPGRADE to 4.12.27

npm install hono@">=4.12.27"

3. If no update is available yet, DOWNGRADE to a release before 4.3.3

npm view hono versions npm install hono@"<4.3.3"

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-59897?

hono: upgrade to 4.12.27. Exact commands for each OS are on this page.

Is CVE-2026-59897 being exploited?

CVE-2026-59897 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-59897 affect?

CVE-2026-59897 affects hono. Severity is medium (CVSS 4.8). Hono is a Web application framework that provides support for any JavaScript runtime. From 4.3.3 before 4.12.27, the AWS API Gateway v1 adapter can drop a distinct repeated request header value because it de-duplicates values using a substr

How urgent is CVE-2026-59897?

Priority 24/100. Remotely exploitable, no login, no user action

Software pages

AWS vulnerabilities

Related CVEs

CVE-2026-59896 MEDIUM 6.5 UPGRADE Hono is a Web application framework that provides support for any JavaScript runtime
CVE-2026-59895 MEDIUM 6.1 UPGRADE Hono is a Web application framework that provides support for any JavaScript runtime

References

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