Vulnerability Description
When a user invokes curl using a schemeless URL combined with `--proto-default` sftp (or scp), a disconnect occurs between the tool layer and libcurl. The tool layer incorrectly infers the URL scheme, which erroneously bypasses the initialization of critical SSH security options like CURLOPT_SSH_HOST_PUBLIC_KEY_SHA256 and CURLOPT_SSH_KNOWNHOSTS. Conversely, the libcurl runtime successfully honors CURLOPT_DEFAULT_PROTOCOL and establishes the connection via SFTP/SCP as specified. Because the tool layer skipped the security configuration, these SSH host verification options are silently omitted, causing curl to connect to an unverified SSH remote host without throwing an error.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Haxx | Curl | >= 7.81.0, < 8.21.0 |
Related Weaknesses (CWE)
References
- https://curl.se/docs/CVE-2026-12064.htmlPatchVendor Advisory
- https://curl.se/docs/CVE-2026-12064.jsonVendor Advisory
- https://hackerone.com/reports/3797526ExploitIssue TrackingThird Party Advisory
- https://hackerone.com/reports/3797526ExploitIssue TrackingThird Party Advisory
FAQ
What is CVE-2026-12064?
CVE-2026-12064 is a vulnerability with a CVSS score of 7.5 (HIGH). When a user invokes curl using a schemeless URL combined with `--proto-default` sftp (or scp), a disconnect occurs between the tool layer and libcurl. The tool layer incorrectly infers the URL scheme,...
How severe is CVE-2026-12064?
CVE-2026-12064 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-12064?
Check the references section above for vendor advisories and patch information. Affected products include: Haxx Curl.