What is CVE-2026-39409?

CVE-2026-39409 is a medium-severity vulnerability in Hono, classified under CWE-180. CVSS score: 5.3/10. Published 2026-04-08.

How severe is CVE-2026-39409?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Hono

CVE-2026-39409

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.12, ipRestriction() does not canonicalize IPv4-mapped IPv6 client addresses (e.g. ::ffff:127.0.0.1) before applying IPv4 allow or deny rule…

EPSS: 0.003 (26.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

Affected products

Hono
Honojs Hono — versions < 4.12.12

Weakness classification (CWE)

CWE-180

References

security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
security-advisories@github.com (Patch, x_refsource_MISC)
security-advisories@github.com (x_refsource_MISC, Release Notes)

Frequently asked questions

What is CVE-2026-39409?: CVE-2026-39409 is a medium-severity vulnerability in Hono, classified under CWE-180. CVSS score: 5.3/10. Published 2026-04-08.
How severe is CVE-2026-39409?: Medium severity. CVSS v3 base score is 5.3 out of 10.