hono: Body Limit Middleware can be bypassed on AWS Lambda by understating Content-Length

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS

• CVE-2026-54288: 0.15% estimated exploitation activity in the next 30 days; percentile 3.94 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The Body Limit Middleware trusts the request's Content-Length header to decide whether a body is within the limit. On AWS Lambda (API Gateway v1/v2, ALB, VPC Lattice, and Lambda@Edge) the body is delivered fully buffered and the adapter builds the request with the client-declared Content-Length, which need not match the actual payload. A client can declare a tiny Content-Length while sending a much larger body, slipping past the limit. Details When Content-Length is present and Transfer-Encoding is absent, the middleware compares the declared value against the limit and passes the request through if it is small enough. On standards-based runtimes the transport enforces that Content-Length matches the body, so this is safe. The Lambda adapters instead reconstruct the request from a buffered payload and copy the client's Content-Length verbatim, so the declared length and the real body size are decoupled. This issue affects applications deployed on AWS Lambda that rely on the…

Published by the source

16 Jun 2026, 14:32 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 12:57 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-rv63-4mwf-qqc2

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-rv63-4mwf-qqc2

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-54288

Advisory: hono: Body Limit Middleware can be bypassed on AWS Lambda by understating `Content-Length`
IDs: CVE-2026-54288, GHSA-rv63-4mwf-qqc2
Record: https://patchnext.com/advisories/cve-2026-54288 (revision 2, source checked 26 Oct 2026, 12:57 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: hono 4.12.25. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm hono: affected < 4.12.25; fixed in 4.12.25

## Suggested inspection (read-only)
- `npm ls hono --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on hono.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-rv63-4mwf-qqc2 (OSV record GHSA-rv63-4mwf-qqc2 lists affected ranges: npm hono >=0 <4.12.25 (fixed))
- Verified: https://github.com/advisories/GHSA-rv63-4mwf-qqc2 (GitHub-reviewed advisory GHSA-rv63-4mwf-qqc2 lists affected ranges: npm hono >=0 <4.12.25)

Commands are suggestions: review each one before running it.