Body-size limit bypass via understated Content-Length
Published Jun 22, 2026 · Updated Jun 22, 2026
Body-limit bypass in Hono before 4.12.25 allows remote attackers to submit oversized request bodies to AWS Lambda applications. The Body Limit Middleware accepts the client-declared Content-Length as the actual size, while Lambda adapters reconstruct a Request around the fully buffered payload without verifying that the values match. Only AWS Lambda deployments using hono/body-limit with hono/aws-lambda or hono/lambda-edge are exposed; accepted payloads remain bounded by AWS request limits but consume extra CPU and memory.
Summary
What happened
Body-limit bypass in Hono before 4.12.25 allows remote attackers to submit oversized request bodies to AWS Lambda applications. The Body Limit Middleware accepts the client-declared Content-Length as the actual size, while Lambda adapters reconstruct a Request around the fully buffered payload without verifying that the values match. Only AWS Lambda deployments using hono/body-limit with hono/aws-lambda or hono/lambda-edge are exposed; accepted payloads remain bounded by AWS request limits but consume extra CPU and memory.
The record
- CVE
- CVE-2026-54288
- Published
- Jun 22, 2026
- Updated
- Jun 22, 2026
- Vendor
- Hono
- Product
- Hono
- Classifications
- CWE-345, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 22, 2026CVE publishedPublication date reported by the CVE source.
- Jun 22, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 4.12.25
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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