CVE-2026-40243: CWE-295: Improper Certificate Validation in lxc incus
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.
AI Analysis
Technical Summary
CVE-2026-40243 describes an improper certificate validation vulnerability (CWE-295) in Incus, a system container and virtual machine manager by lxc. In versions before 7.0.0, the OVN database connection logic disables Go standard TLS server verification and replaces it with custom verification that fails to anchor trust in the configured CA certificate. Instead, the verification root set is constructed from certificates supplied by the peer, allowing acceptance of rogue self-signed certificates. This enables an attacker with network access to impersonate the OVN database endpoint. The vulnerability is resolved in version 7.0.0.
Potential Impact
An attacker positioned on the management network who can impersonate or intercept the OVN database endpoint can present a rogue certificate chain that Incus versions prior to 7.0.0 will accept as valid. This defeats the intended CA-based trust model and allows endpoint impersonation. The CVSS 4.0 score is 2.3, indicating low severity with attack vector requiring adjacent network access and high attack complexity. There is no indication of known exploits in the wild.
Mitigation Recommendations
This vulnerability is fixed in Incus version 7.0.0. Users should upgrade to version 7.0.0 or later to resolve this issue. No official patch or temporary fix is documented beyond upgrading. Until upgraded, deployments should consider restricting network access to the OVN database endpoint to trusted hosts to reduce risk.
CVE-2026-40243: CWE-295: Improper Certificate Validation in lxc incus
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.
CVSS v4.0
Score 2.3low
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-40243 describes an improper certificate validation vulnerability (CWE-295) in Incus, a system container and virtual machine manager by lxc. In versions before 7.0.0, the OVN database connection logic disables Go standard TLS server verification and replaces it with custom verification that fails to anchor trust in the configured CA certificate. Instead, the verification root set is constructed from certificates supplied by the peer, allowing acceptance of rogue self-signed certificates. This enables an attacker with network access to impersonate the OVN database endpoint. The vulnerability is resolved in version 7.0.0.
Potential Impact
An attacker positioned on the management network who can impersonate or intercept the OVN database endpoint can present a rogue certificate chain that Incus versions prior to 7.0.0 will accept as valid. This defeats the intended CA-based trust model and allows endpoint impersonation. The CVSS 4.0 score is 2.3, indicating low severity with attack vector requiring adjacent network access and high attack complexity. There is no indication of known exploits in the wild.
Mitigation Recommendations
This vulnerability is fixed in Incus version 7.0.0. Users should upgrade to version 7.0.0 or later to resolve this issue. No official patch or temporary fix is documented beyond upgrading. Until upgraded, deployments should consider restricting network access to the OVN database endpoint to trusted hosts to reduce risk.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-10T17:31:45.785Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69fba9cccbff5d86105e9c35
Added to database: 05/06/2026, 20:51:24 UTC
Last enriched: 05/14/2026, 03:49:25 UTC
Last updated: 07/31/2026, 19:22:58 UTC
Views: 124
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