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.
References
https://curl.se/docs/CVE-2026-9547.html
https://curl.se/docs/CVE-2026-9547.json
https://hackerone.com/reports/3751712
https://hackerone.com/reports/3751712
CVSS impact metrics
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
7.4 · High
Information
Source identifier
2499f714-1537-4658-8207-48ae4bb9eae9
Vulnerability status
Modified
Published
2026-07-03T07:16:25.990Z
3 months agoLast modified
2026-09-15T07:16:35.310Z
3 weeks ago