Medium severity · published Jun 22, 2026
CVE-2026-54288
Hono: Body Limit Middleware can be bypassed on AWS Lambda by understating `Content-Length`
6.5
CVSS
0.1%
EPSS
No
On KEV
Description
Hono is a Web application framework that provides support for any JavaScript runtime. Prior to 4.12.25, 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. This vulnerability is fixed in 4.12.25.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 4% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
HO
hono · honojs
< 4.12.25 · source: vendor
Affected product
HO
hono
honojs
More from hono
9.8
CVE-2026-29045
Hono: Arbitrary file access via serveStatic vulnerability
8.1
CVE-2025-62610
Hono Improperly Authorizes JWT Audience Validation
7.5
CVE-2026-39408
Hono has a path traversal in toSSG() allows writing files outside the output directory
7.5
CVE-2026-27700
Hono is Vulnerable to Authentication Bypass by IP Spoofing in AWS Lambda ALB conninfo
7.5
CVE-2025-58362
Hono contains a flaw in URL path parsing, potentially leading to path confusion