CVE-2026-40243

Description

Incus is a system container and virtual machine manager. In versions before 7.0.0, broken TLS validation logic in the OVN database connection logic can allow connections to an attacker's OVN database. The OVN client implementations disable Go standard TLS server verification and replace it with custom peer-certificate verification logic. That replacement verifier does not anchor trust in the configured CA certificate. Instead, it constructs the verification root set from certificates supplied by the peer during the handshake, so the configured CA is parsed but not used as the trust anchor for the final verification decision. In OVN-enabled deployments that use these SSL database connection paths, an attacker able to impersonate or intercept the OVN endpoint on the management network can present a rogue self-signed certificate chain, and Incus will accept this certificate as valid. This issue defeats the intended CA-based trust model for OVN database connections and permits endpoint impersonation by an active attacker in a suitable network position. This issue is fixed in version 7.0.0.

How to fix CVE-2026-40243

To remediate CVE-2026-40243, upgrade the affected package to a fixed version below.

• —upgrade to 6.0.4-2+deb13u7 or later
• —upgrade to 7.0.0 or later

Is CVE-2026-40243 being exploited?

Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.

Affected packages (2)

• from 0, < 6.0.4-2+deb13u7
• from 0, < 7.0.0

CVSS scores

References (8)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2026-40243
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2026-40243
• PATCHgithub.com/lxc/incus
• WEBgithub.com/lxc/incus/blob/v6.22.0/internal/server/network/ovn/ovn_icnb.go