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.
Published: 2026-07-03
Score: 7.4 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Ubuntu USN Ubuntu USN USN-8487-1 curl vulnerabilities
History

Tue, 07 Jul 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-347
References
Metrics threat_severity

None

 threat_severity

Important

Mon, 06 Jul 2026 22:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-295
CWE-307

Mon, 06 Jul 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Mon, 06 Jul 2026 04:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-295
CWE-307

Sun, 05 Jul 2026 20:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-295

Sun, 05 Jul 2026 09:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-295

Sun, 05 Jul 2026 01:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-295

Sat, 04 Jul 2026 09:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-295

Fri, 03 Jul 2026 21:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-287

Fri, 03 Jul 2026 10:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-287

Fri, 03 Jul 2026 08:30:00 +0000

Type Values Removed Values Added
First Time appeared Curl
Curl curl
Vendors & Products Curl
Curl curl

Fri, 03 Jul 2026 06:45:00 +0000

Type Values Removed Values Added
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.
Title SSH improper host validation
References

Subscriptions

Curl Curl
cve-icon MITRE

Status: PUBLISHED

Assigner: curl

Published:

Updated: 2026-07-06T16:48:14.469Z

Reserved: 2026-05-26T06:45:27.665Z

Link: CVE-2026-9547

cve-icon Vulnrichment

Updated: 2026-07-06T16:48:09.620Z

cve-icon NVD

No data.

cve-icon Redhat

Severity : Important

Publid Date: 2026-07-03T06:18:44Z

Links: CVE-2026-9547 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-07-07T19:45:14Z

Weaknesses