CVE-2026-54287CWE-116

Hono: AWS Lambda adapter merges multiple `Set-Cookie` headers into one value, dropping cookies on ALB single-header and Lattice

Medium · published June 22, 2026

CVSS v3.1
5.3
EPSS
0%
Percentile
22.6
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00310 · 22.6th percentile
Weakness
CWE-116 · Improper Encoding or Escaping of Output
Published
2026-06-22T17:13Z
EPSS history
Timeline
  • 22 JUN 17:13Z
    Hono: AWS Lambda adapter merges multiple `Set-Cookie` headers into one value, dropping cookies on ALB single-header and Lattice
    cvelistv5