CVE-2026-40243: GO-2026-5319 - Incus has an OVN TLS Verification that Accepts Peer-Supplied Roots in github.com/lxc/incus

CVE-2026-40243 · Severity: medium · CVSS 4.8 · Published 2026-05-06

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.

Technologies: github.com/lxc/incus (Go), github.com/lxc/incus/v6 (Go), github.com/lxc/incus/v6/cmd/incusd (Go), github.com/lxc/incus/v7 (Go), Linuxcontainers Incus. Vendors: Go, Linuxcontainers.

Quick answers

Is CVE-2026-40243 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-40243 being exploited in the wild.
How severe is CVE-2026-40243?
Medium severity, with a CVSS score of 4.8, published 6 May 2026.
Which products and versions are affected?
github.com/lxc/incus (Go) SEMVER:introduced=0; github.com/lxc/incus/v6 (Go) SEMVER:introduced=0; github.com/lxc/incus/v6/cmd/incusd (Go) SEMVER:introduced=0,fixed=7.0.0; github.com/lxc/incus/v7 (Go) SEMVER:introduced=0,fixed=7.0.0.
Is there a fix for CVE-2026-40243?
Yes. github.com/lxc/incus/v6/cmd/incusd (Go): upgrade to 7.0.0 or later; github.com/lxc/incus/v7 (Go): upgrade to 7.0.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
Am I affected by CVE-2026-40243?
Check whether you run github.com/lxc/incus (Go), github.com/lxc/incus/v6 (Go), github.com/lxc/incus/v6/cmd/incusd (Go) or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • github.com/lxc/incus/v6/cmd/incusd (Go): upgrade to 7.0.0 or later
    go get github.com/lxc/incus/v6/cmd/incusd@v7.0.0
  • github.com/lxc/incus/v7 (Go): upgrade to 7.0.0 or later
    go get github.com/lxc/incus/v7@v7.0.0

Affected products

  • github.com/lxc/incus (Go) SEMVER:introduced=0
  • github.com/lxc/incus/v6 (Go) SEMVER:introduced=0
  • github.com/lxc/incus/v6/cmd/incusd (Go) SEMVER:introduced=0,fixed=7.0.0
  • github.com/lxc/incus/v7 (Go) SEMVER:introduced=0,fixed=7.0.0
  • Linuxcontainers Incus

Identifiers

  • CVE-2026-40243
  • GHSA-c839-4qxr-j4x3
  • GO-2026-5319

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