CVE-2026-9547

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure, data tampering.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-07-03 07:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-09-15 07:16 UTC Last updatedMost recent change to the record

Details

Published

2026-07-03 07:16 UTC

Last modified

2026-09-15 07:16 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-297

Record status

Modified

Affected

• Haxx Curl < 8.21.0

Attack profile CVSS 3.1 · 7.4

Attack vector

Network

Complexity

High

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None