CVE-2026-9547
Last modified
CVE-2026-9547 is a high-severity vulnerability rated 7.4/10 on the CVSS scale. 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. EPSS estimates a 0.38% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Haxx | Curl | >= 7.69.0, < 8.21.0 |
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
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
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How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
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