Medium severity · published May 28, 2026
CVE-2026-47675
Hono: Cookie helper does not sanitize sameSite and priority, allowing Set-Cookie injection
5.3
CVSS
0.2%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 12% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
HO
hono · honojs
< 4.12.21 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-47675
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-47675
Vendor Advisory
https://github.com/honojs/hono/security/advisories/GHSA-3hrh-pfw6-9m5x
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