CVE-2026-71849Network attack vector

Information disclosure via forwarded connection-scoped headers

Published Aug 7, 2026 · Updated Aug 7, 2026

Information disclosure in Hono 4.7.0 through 4.12.33 allows remote attackers to receive connection-scoped origin headers. The proxy() function copies an origin response into new Headers and deletes only its fixed hop-by-hop list, leaving fields named by Connection intact. Exposure requires an application route using hono/proxy and an origin response that declares custom hop-by-hop names; disclosed data is limited to metadata carried in those headers.

CVSS severity3.7
Low
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Information disclosure in Hono 4.7.0 through 4.12.33 allows remote attackers to receive connection-scoped origin headers. The proxy() function copies an origin response into new Headers and deletes only its fixed hop-by-hop list, leaving fields named by Connection intact. Exposure requires an application route using hono/proxy and an origin response that declares custom hop-by-hop names; disclosed data is limited to metadata carried in those headers.

The record

CVE
CVE-2026-71849
Published
Aug 7, 2026
Updated
Aug 7, 2026
Vendor
Hono
Product
Hono
Classifications
CWE-200, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 7, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 4.7.0, < 4.12.34

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hono · Honoversion=>= 4.7.0, < 4.12.34

Published CVSS scores

3.7GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-200Exposure of Sensitive Information to an Unauthorized Actor
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo