Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Haxx | Curl | >= 7.69.0, < 8.21.0 |
References
- https://curl.se/docs/CVE-2026-9547.htmlPatchVendor Advisory
- https://curl.se/docs/CVE-2026-9547.jsonVendor Advisory
- https://hackerone.com/reports/3751712ExploitIssue TrackingThird Party Advisory
- https://hackerone.com/reports/3751712ExploitIssue TrackingThird Party Advisory
FAQ
What is CVE-2026-9547?
CVE-2026-9547 is a vulnerability with a CVSS score of 7.4 (HIGH). 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...
How severe is CVE-2026-9547?
CVE-2026-9547 has been rated HIGH with a CVSS base score of 7.4/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-9547?
Check the references section above for vendor advisories and patch information. Affected products include: Haxx Curl.