Authentication Bypass in github.com/lxc/incus/v6/cmd/incusd (CVE-2026-40243)
Summary
Authentication bypass in github.com/lxc/incus/v6/cmd/incusd (CVE-2026-40243). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 7.0.0 or later.
Original description
The description as published by the source.
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.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-40243 has been found in github.com/lxc/incus/v6/cmd/incusd.
Risk of unauthorized operations or information disclosure. CVSS score: 4.8/10.
What to do: upgrade github.com/lxc/incus/v6/cmd/incusd to 7.0.0 or later.
If unsure, ask your IT team or search "github.com/lxc/incus/v6/cmd/incusd CVE-2026-40243" on the vendor's site.
CVE-2026-40243 (github.com/lxc/incus/v6/cmd/incusd) — CWE-287 / CVSS v3 4.8
Attack vector: local / no user interaction
Patched: 7.0.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Authentication bypass (CWE-287) exists in github.com/lxc/incus/v6/cmd/incusd.
Check the vendor advisory for the affected versions of github.com/lxc/incus/v6/cmd/incusd.
Severity: Medium (CVSS 4.8/10). Risk of unauthorized operations or information disclosure.
Update to 7.0.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'github.com/lxc/incus/v6/cmd/incusd' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'github.com/lxc/incus/v6/cmd/incusd' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
github.com/lxc/incus/v6/cmd/incusdを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade github.com/lxc/incus/v6/cmd/incusd to 7.0.0ステージング環境で 7.0.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-40243 incus Fixed in: 6.0.4-2+deb13u7
- Ubuntu UBUNTU-CVE-2026-40243 incus
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- web github.com
- web github.com
- web github.com
- web github.com
- web github.com