CVE-2026-112816: CVE-2026-112816: Improper certificate validation in the HTTPS listener in Canonical LXD 4.0.14, 5.0.10, 5.2…

CVE-2026-112816 at a glance

CVE-2026-112816 is a critical-severity vulnerability in the affected product, with a CVSS 4.0 base score of 10. NVD published it on 2026-10-30 and classifies the weakness as CWE-295. Public exploit code: 3 public GitHub proof-of-concept repositories from 3 accounts, with the earliest exploit evidence dated 2026-10-31. FIRST EPSS puts the probability of exploitation activity in the next 30 days at 0.30% (percentile 23.1, scored 2026-11-03). NVD does not list a fixed version, so the vendor advisory is the reference for the fix. CVERadar maps 1 MITRE ATT&CK technique across Credential Access and Collection, inferred from the CWE and the description. Its CVERadar threat level is 54/100.

What it is

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.

Exploitation evidence

First exploit evidence seen: 2026-10-31 (earliest date across the sources below).

Exploited in the wild

No source on this site lists in-the-wild exploitation yet (CISA KEV, VulnCheck KEV).

Public exploit code

GitHub proof-of-concept repositories

3 public repositories from 3 accounts, first seen 2026-10-31. Most starred: MrNarsus/cve-2026-112816-poc (3 stars), view the MrNarsus/cve-2026-112816-poc repository on GitHub.

Verify before running: public PoCs can be malicious. Read the code and only run it in an isolated lab. A PoC means exploit code is public, not that this CVE is exploited in the wild.

Sources: nomi-sec/PoC-in-GitHub.

Patches, mitigations and detection

Fixed versions

NVD does not list a fixed version for this CVE. Use the vendor advisory below.

Derived from the NVD CPE configuration (versionEndExcluding / versionEndIncluding). Always confirm with the vendor advisory.

Vendor advisories and patches

No vendor-tagged reference yet; see the full reference list.

MITRE ATT&CK mitigations for this chain

• M1037 Filter Network Traffic (for T1557) : Use network appliances and host-based security software to block network traffic that is not necessary within the environment, such as legacy protocols that may be leveraged for AiTM conditions.
• M1041 Encrypt Sensitive Information (for T1557) : Ensure that all wired and/or wireless traffic is encrypted appropriately. Use best practices for authentication protocols, such as Kerberos, and ensure web traffic that may contain credentials is protected by SSL/TLS.
• M1035 Limit Access to Resource Over Network (for T1557) : Limit access to network infrastructure and resources that can be used to reshape traffic or otherwise produce AiTM conditions.
• M1042 Disable or Remove Feature or Program (for T1557) : Disable legacy network protocols that may be used to intercept network traffic if applicable, especially those that are not needed within an environment.
• M1017 User Training (for T1557) : Train users to be suspicious about certificate errors. Adversaries may use their own certificates in an attempt to intercept HTTPS traffic. Certificate errors may arise when the application’s certificate does not match the one expected by the host.
• M1031 Network Intrusion Prevention (for T1557) : Network intrusion detection and prevention systems that can identify traffic patterns indicative of AiTM activity can be used to mitigate activity at the network level.
• M1030 Network Segmentation (for T1557) : Network segmentation can be used to isolate infrastructure components that do not require broad network access. This may mitigate, or at least alleviate, the scope of AiTM activity.

Detection Generic guidance

• Credential Access: Monitor for credential dumping, unusual LSASS access and sudden authentication from new sources.
• Collection: Watch for bulk reads of databases, file shares or mailboxes by the affected service.

Response checklist Generic guidance

1. Inventory: find every instance of the affected product and version (include internet-facing and forgotten ones).
2. Patch or mitigate per the vendor advisory; if you cannot patch, remove internet exposure or apply the vendor workaround.
3. Assume compromise if the system was exposed before patching: hunt for the indicators in the advisory and review logs back to the disclosure date.
4. Rotate credentials and secrets stored on or used by the affected system if compromise cannot be ruled out.