What’s Vulnerable › Vulnerabilities

CVE-2026-40243: Incus OVN TLS verification accepts peer-supplied roots and permits endpoint impersonation

• Severity: medium (CVSS 4.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-05-06 · updated 2026-10-26
• Weakness: CWE-295

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.

Affected products

• lxc incus: before 7.0.0 — fixed in 7.0.0

How to fix

Upgrade to a fixed version: lxc incus 7.0.0. Check the vendor advisory for mitigations.

References

• https://github.com/lxc/incus/blob/v6.22.0/internal/server/network/ovn/ovn_icnb.go
• https://github.com/lxc/incus/blob/v6.22.0/internal/server/network/ovn/ovn_icsb.go
• https://github.com/lxc/incus/blob/v6.22.0/internal/server/network/ovn/ovn_nb.go
• https://github.com/lxc/incus/blob/v6.22.0/internal/server/network/ovn/ovn_sb.go
• https://github.com/lxc/incus/security/advisories/GHSA-c839-4qxr-j4x3
• https://github.com/lxc/incus/security/advisories/GHSA-c839-4qxr-j4x3

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