CVE-2026-54287: hono: AWS Lambda adapter merges multiple `Set-Cookie` headers into one value, dropping cookies on ALB single-header and Lattice

June 16, 2026 (updated July 21, 2026)

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.

References

github.com/advisories/GHSA-j6c9-x7qj-28xf
github.com/honojs/hono/security/advisories/GHSA-j6c9-x7qj-28xf
nvd.nist.gov/vuln/detail/CVE-2026-54287

Code Behaviors & Features

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