CVE-2026-33805
@fastify/reply-from vulnerable to connection header abuse enabling stripping of proxy-added headers
Description
@fastify/reply-from v12.6.1 and earlier and @fastify/http-proxy v11.4.3 and earlier process the client's Connection header after the proxy has added its own headers via rewriteRequestHeaders. This allows attackers to retroactively strip proxy-added headers from upstream requests by listing them in the Connection header value. Any header added by the proxy for routing, access control, or security purposes can be selectively removed by a client. @fastify/http-proxy is also affected as it delegates to @fastify/reply-from. Upgrade to @fastify/reply-from v12.6.2 or @fastify/http-proxy v11.4.4 or later.
INFO
Published Date :
April 15, 2026, 10:13 a.m.
Last Modified :
April 15, 2026, 10:13 a.m.
Remotely Exploit :
No
Source :
openjs
Affected Products
The following products are affected by CVE-2026-33805
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | CRITICAL | ce714d77-add3-4f53-aff5-83d477b104bb |
Solution
- Upgrade @fastify/reply-from to version 12.6.2 or later.
- Upgrade @fastify/http-proxy to version 11.4.4 or later.
- Ensure the Connection header is handled securely.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-33805 vulnerability anywhere in the article.