CVE-2026-9547

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.

Why is this CVE low priority?

Upstream defined this as low severity

Learn more about Ubuntu priority

Status

Show unmaintained releases

Package	Ubuntu Release	Status
curl	26.04 LTS resolute	Fixed 8.18.0-1ubuntu2.2
	25.10 questing	Fixed 8.14.1-2ubuntu1.4
	24.04 LTS noble	Fixed 8.5.0-2ubuntu10.10
	22.04 LTS jammy	Fixed 7.81.0-1ubuntu1.25
	20.04 LTS focal	Not affected
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
curl	Upstream: 0b8dbbc

References

Related Ubuntu Security Notices (USN)

USN-8487-1
curl vulnerabilities
30 June 2026