CVE-2026-47675

Description

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, the serialize() function in hono/cookie validates domain and path options against characters that corrupt Set-Cookie header syntax (;, \r, \n), but does not apply the same validation to sameSite and priority. An application that passes user-controlled input into either option may produce a Set-Cookie response header containing attacker-chosen additional attributes. This vulnerability is fixed in 4.12.21.

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CVSS v3.1 Score

4.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

EPSS — Exploit Prediction

0.0022

Probability of exploitation

0.12%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-113 CWE-113

CWE-1287 CWE-1287

Affected Products

Vendor	Product	Versions
hono	hono	< 4.12.21

References

Advisories & Patches

https://github.com/honojs/hono/security/advisories/GHSA-3hrh-pfw6-9m5x

Frequently Asked Questions

What is CVE-2026-47675? +

Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.21, the serialize() function in hono/cookie validates domain and path options against characters that corrupt Set-Cookie header syntax (;, \r, \n), but does not apply the same validation to sameSite and priority. An application that passes user-controlled input into either option may produce a Set-Cookie response header containing attacker-chosen additional attributes. This vulnerability is fixed in 4.12.21. It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2026-47675? +

CVE-2026-47675 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0022, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-47675? +

CVE-2026-47675 affects products from hono, specifically: hono. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-47675? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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