CVE-2026-86410

Description

A flaw in the curl command line tool's logic makes it only set SSH host verification options when interacting directly using SFTP or SCP, and not as a result of following a redirect. This means `--knownhosts`, `--hostpubsha256`, and `--hostpubmd5` are never installed when the initial URL is HTTPS. If `--location` and `--proto-redir +sftp` is used and the server returns a `Location: sftp://example.com` redirect, the SFTP connection proceeds without any of the user's requested SSH host verification methods.

Read the notes from the security team

Why is this CVE low priority?

Upstream defined this as low severity

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Status

Show unmaintained releases

Package	Ubuntu Release	Status
curl	26.04 LTS resolute	Fixed 8.18.0-1ubuntu2.8
	24.04 LTS noble	Not affected
	22.04 LTS jammy	Not affected
	20.04 LTS focal	Not affected
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected

Notes

charlescochran

Ubuntu builds jammy/noble with libssh instead of libssh2. This falls back to the default known_hosts when no --knownhosts is set, rendering the issue effectively not-affected on these versions (even though advisory says >= 7.81.0 is 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: 6ae9bef

References

Related Ubuntu Security Notices (USN)

USN-8927-1
curl vulnerabilities
14 October 2026