CVE-2026-47675

Hono: Cookie helper does not sanitize sameSite and priority, allowing Set-Cookie injection

MEDIUM
5.3
CVSS Score
Published: May 28, 2026 at 03:28 PM UTC
Updated: October 14, 2026 at 08:10 PM UTC
2 products affected across 2 vendorsHonoHono

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.2%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 4.12.21
v < 4.12.21
Affected range stops below 4.12.21, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (1)

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

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-113CWE-1287

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