How severe is CVE-2026-59897?

CVE-2026-59897 has a CVSS 3.x base score of 4.8, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-59897 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (7th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-59897?

CVE-2026-59897 affects Hono. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-59897?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-59897 published?

CVE-2026-59897 was published on 2026-07-08 and last updated on 2026-07-10.

CVE-2026-59897

CVE-2026-59897 is a medium-severity vulnerability in Hono with a CVSS 3.x base score of 4.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-348.

Key facts

Severity: Medium (CVSS 3.x base score 4.8)
EPSS exploit prediction: 0% (7th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-348
Affected product: Hono
Published: 2026-07-08
Last modified: 2026-07-10

Description

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 data. This issue is fixed in version 4.12.27.

Frequently asked questions

What is CVE-2026-59897?: 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 data. This issue is fixed in version 4.12.27.
How severe is CVE-2026-59897?: CVE-2026-59897 has a CVSS 3.x base score of 4.8, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-59897 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (7th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-59897?: CVE-2026-59897 affects Hono. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-59897?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-59897 published?: CVE-2026-59897 was published on 2026-07-08 and last updated on 2026-07-10.

References

Affected products (1)

cpe:2.3:a:hono:hono:*:*:*:*:*:node.js:*:*

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