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Fencer Vulns
medium 5.3

CVE-2025-59139 json

Hono has Body Limit Middleware Bypass

published 2025-09-12 13 mo ago modified 2026-09-10 1 mo ago also EUVD-2025-29042 , GHSA-92vj-g62v-jqhh

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 39%
public exploits
0
none known

Summary

Hono is a Web application framework that provides support for any JavaScript runtime. In versions prior to 4.9.7, a flaw in the `bodyLimit` middleware could allow bypassing the configured request body size limit when conflicting HTTP headers were present. The middleware previously prioritized the `Content-Length` header even when a `Transfer-Encoding: chunked` header was also included. According to the HTTP specification, `Content-Length` must be ignored in such cases. This discrepancy could allow oversized request bodies to bypass the configured limit. Most standards-compliant runtimes and reverse proxies may reject such malformed requests with `400 Bad Request`, so the practical impact depends on the runtime and deployment environment. If body size limits are used as a safeguard against large or malicious requests, this flaw could allow attackers to send oversized request bodies. The primary risk is denial of service (DoS) due to excessive memory or CPU consumption when handling very large requests. The implementation has been updated to align with the HTTP specification, ensuring that `Transfer-Encoding` takes precedence over `Content-Length`. The issue is fixed in Hono v4.9.7, and all users should upgrade immediately.

Patch / fix

  • npm hono 4.9.7
  • hono hono 4.9.7

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
13 mo ago

Exploit prediction

0.45% chance of exploitation in the next 30 days, higher than 39% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
GitHub 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
npm hono
<4.9.7
4.9.7

Affected products

  • honojs hono

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.