Vulnerability · Published May 6, 2026 · Assigned by GitHub_M
CVE-2026-40243Incus OVN TLS verification accepts peer-supplied roots and permits endpoint impersonation
Low 2.3
In plain English
A low-severity improper certificate validation in incus from lxc. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 7% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.24 | incus | 7.0.0-r0 | ALPINE-CVE-2026-40243 |
| Debian:13 | incus | 6.0.4-2+deb13u7 | DEBIAN-CVE-2026-40243 |
| Debian:14 | incus | 7.0.0-1 | DEBIAN-CVE-2026-40243 |
| Go | github.com/lxc/incus | no fix listed | GO-2026-5319 |
| Go | github.com/lxc/incus/v6 | no fix listed | GO-2026-5319 |
| Go | github.com/lxc/incus/v6/cmd/incusd | 7.0.0 | GHSA-c839-4qxr-j4x3 |
| Go | github.com/lxc/incus/v7 | 7.0.0 | GO-2026-5319 |
| Ubuntu:25.10 | incus | no fix listed | UBUNTU-CVE-2026-40243 |
| Ubuntu:26.10 | incus | no fix listed | UBUNTU-CVE-2026-40243 |
Affected products (as reported)
Weakness: CWE-295 · Vector: CVSS:4.0/AV:A/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
References
- https://github.com/lxc/incus/security/advisories/GHSA-c839-4qxr-j4x3 x_refsource_CONFIRM
- https://github.com/lxc/incus/blob/v6.22.0/internal/server/network/ovn/ovn_icnb.go x_refsource_MISC
- https://github.com/lxc/incus/blob/v6.22.0/internal/server/network/ovn/ovn_icsb.go x_refsource_MISC
- https://github.com/lxc/incus/blob/v6.22.0/internal/server/network/ovn/ovn_nb.go x_refsource_MISC
- https://github.com/lxc/incus/blob/v6.22.0/internal/server/network/ovn/ovn_sb.go x_refsource_MISC