Medium severity · published Jun 22, 2026
CVE-2026-54287
Hono: AWS Lambda adapter merges multiple `Set-Cookie` headers into one value, dropping cookies on ALB single-header and Lattice
5.3
CVSS
0.3%
EPSS
No
On KEV
Description
Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.25, on AWS Lambda, the ALB single-header response and the VPC Lattice v2 response join multiple Set-Cookie headers into one comma-separated value. Because commas also appear inside cookie attributes (for example Expires dates), clients cannot split the value back into individual cookies and silently drop or misparse them. This vulnerability is fixed in 4.12.25.
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)0.3% · higher than 24% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
HO
hono · honojs
< 4.12.25 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-54287
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-54287
github.com
https://github.com/honojs/hono/security/advisories/GHSA-j6c9-x7qj-28xf
More from hono
9.8
CVE-2026-29045
Hono: Arbitrary file access via serveStatic vulnerability
8.1
CVE-2025-62610
Hono Improperly Authorizes JWT Audience Validation
7.5
CVE-2026-39408
Hono has a path traversal in toSSG() allows writing files outside the output directory
7.5
CVE-2026-27700
Hono is Vulnerable to Authentication Bypass by IP Spoofing in AWS Lambda ALB conninfo
7.5
CVE-2025-58362
Hono contains a flaw in URL path parsing, potentially leading to path confusion