Vulnerability · Published Aug 7, 2026 · Assigned by GitHub_M
CVE-2026-71849Hono: Proxy Helper does not remove response headers listed in the `Connection` header
Low 3.7
In plain English
A low-severity information exposure in hono from honojs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 29% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Hono is a Web application framework that provides support for any JavaScript runtime. From 4.7.0 to 4.12.33, the Proxy Helper proxy() function in hono/proxy does not remove response headers named by the origin's Connection header. Per RFC 9110 Section 7.6.1, an intermediary must remove the header fields listed in a message's Connection header field before forwarding the message, in addition to the well known hop by hop headers, but the proxy() function only removed the well known hop by hop headers, including Connection itself, from origin responses. A client may therefore receive response headers that the origin intended only for its immediate peer, disclosing connection scoped or internal metadata contained in such headers, when an application proxies responses from an origin that declares additional, non standard headers as hop by hop via the Connection response header. This issue is fixed in version 4.12.34.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | hono | 4.12.34 | GHSA-79qm-7rj5-m7r9 |
Affected products (as reported)
Weakness: CWE-200 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
References
- https://github.com/honojs/hono/security/advisories/GHSA-79qm-7rj5-m7r9 x_refsource_CONFIRM
- https://github.com/honojs/hono/commit/720b566290793d4358bf39843adcb7cf4da4548f x_refsource_MISC
- https://github.com/honojs/hono/releases/tag/v4.12.34 x_refsource_MISC