Vulnerability · Published Jul 3, 2026 · Assigned by curl
CVE-2026-9547SSH improper host validation
High 7.4
In plain English
A high-severity security flaw in curl from curl. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 30% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:9 | curl | 7.76.1-40.el9_8.5 | ALSA-2026:55439 |
| AlmaLinux:9 | curl-minimal | 7.76.1-40.el9_8.5 | ALSA-2026:55439 |
| AlmaLinux:9 | libcurl | 7.76.1-40.el9_8.5 | ALSA-2026:55439 |
| AlmaLinux:9 | libcurl-devel | 7.76.1-40.el9_8.5 | ALSA-2026:55439 |
| AlmaLinux:9 | libcurl-minimal | 7.76.1-40.el9_8.5 | ALSA-2026:55439 |
| Alpine:v3.23 | curl | 8.22.0-r0 | ALPINE-CVE-2026-9547 |
| Alpine:v3.24 | curl | 8.21.0-r0 | ALPINE-CVE-2026-9547 |
| Debian:12 | curl | no fix listed | DEBIAN-CVE-2026-9547 |
| Debian:13 | curl | no fix listed | DEBIAN-CVE-2026-9547 |
| Debian:14 | curl | 8.21.0~rc2-1 | DEBIAN-CVE-2026-9547 |
| Rocky Linux:9 | curl | 0:7.76.1-40.el9_8.5 | RLSA-2026:55439 |
| Ubuntu:22.04:LTS | curl | 7.81.0-1ubuntu1.25 | UBUNTU-CVE-2026-9547 |
| Ubuntu:24.04:LTS | curl | 8.5.0-2ubuntu10.10 | UBUNTU-CVE-2026-9547 |
| Ubuntu:25.10 | curl | 8.14.1-2ubuntu1.4 | UBUNTU-CVE-2026-9547 |
| Ubuntu:26.04:LTS | curl | 8.18.0-1ubuntu2.2 | UBUNTU-CVE-2026-9547 |
Affected products (as reported)
Weakness: CWE-297 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N