Improper Encoding or Escaping of Output in hono - CVE-2026-54287
Published: July 21, 2026
Vulnerability identifier: #VU138921
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-54287
CWE-ID: CWE-116
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Hono
Affected software:
hono
hono
Detailed vulnerability description
The vulnerability allows a remote attacker to modify data on the system.
The vulnerability exists due to 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. A remote attacker can trigger improper encoding or escaping of output to modify data on the system.
How to mitigate CVE-2026-54287
Install updates from vendor's website.