CVE-2026-9547
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.33%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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 3.1
- 7.4 HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- EPSS
- 0.33% probability · 25th percentile
- CISA KEV
- Not listed
- Affected
- haxx/curl
- Source
- 2499f714-1537-4658-8207-48ae4bb9eae9
References
- https://curl.se/docs/CVE-2026-9547.htmlPatch, Vendor Advisory
- https://curl.se/docs/CVE-2026-9547.jsonVendor Advisory
- https://hackerone.com/reports/3751712Exploit, Issue Tracking, Third Party Advisory
- https://hackerone.com/reports/3751712Exploit, Issue Tracking, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.