CVE-2026-9547 SSH improper host validation
Attackers can bypass SSH host key validation in libcurl-based applications using SCP or SFTP, enabling man-in-the-middle attacks.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-9547?
CVE-2026-9547 is a high-severity vulnerability in Haxx Curl, published on 3 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
When a libcurl-based application performs transfers via `SCP://` or `SFTP://` and utilizes the `CURLOPT_SSH_KEYFUNCTION` callback, it may silently accept an untrusted server. This vulnerability occurs when a server presents a host key type that does not match the specific key type already recorded for that host in the `known_hosts` file. Instead of rejecting the mismatch, the callback mechanism fails to properly enforce the restriction, allowing the connection to succeed without warning and risking a potential man-in-the-middle attack.
Weakness: CWE-297
Which versions are affected by CVE-2026-9547?
It affects 1 product.
Products include Haxx Curl.
How do I fix CVE-2026-9547?
Upgrade to a fixed version.
Is CVE-2026-9547 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-9547 exists.
Other vulnerabilities in Haxx Curl
Sources
Also known as ALPINE-CVE-2026-9547, BELL-CVE-2026-9547, CURL-CVE-2026-9547, DEBIAN-CVE-2026-9547, ECHO-07b2-9e60-e1ba, GHSA-xq9p-gxg6-f7q6 and 11 more.