CVE-2026-54287
MEDIUMHono: AWS Lambda adapter merges multiple `Set-Cookie` headers into one value, dropping cookies on ALB single-header and Lattice
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
hononpmDescription
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | hono | all versions | 4.12.25 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hono. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update hono to 4.12.25 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54287 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-54287 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-54287. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-54287 in your dependencies?
O3 detects CVE-2026-54287 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.