lxc incus up to 6.0.5/6.20.0 YAML Configuration crlf injection

Summaryinfo

A vulnerability was found in lxc incus up to 6.0.5/6.20.0 and classified as problematic. This issue affects some unknown processing of the component YAML Configuration Handler. Such manipulation leads to crlf injection. This vulnerability is referenced as CVE-2026-23953. The attack needs to be initiated within the local network. No exploit is available.

Detailsinfo

A vulnerability was found in lxc incus up to 6.0.5/6.20.0 and classified as problematic. Affected by this issue is an unknown code of the component YAML Configuration Handler. The manipulation with an unknown input leads to a crlf injection vulnerability. Using CWE to declare the problem leads to CWE-93. The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Incus is a system container and virtual machine manager. In versions 6.20.0 and below, a user with the ability to launch a container with a custom YAML configuration (e.g a member of the ‘incus’ group) can create an environment variable containing newlines, which can be used to add additional configuration items in the container’s lxc.conf due to newline injection. This can allow adding arbitrary lifecycle hooks, ultimately resulting in arbitrary command execution on the host. Exploiting this issue on IncusOS requires a slight modification of the payload to change to a different writable directory for the validation step (e.g /tmp). This can be confirmed with a second container with /tmp mounted from the host (A privileged action for validation only). A fix is planned for versions 6.0.6 and 6.21.0, but they have not been released at the time of publication.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-23953 since 01/19/2026. The exploitation is known to be easy. The attack needs to be initiated within the local network. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 01/23/2026).

The vulnerability scanner Nessus provides a plugin with the ID 296221 (Linux Distros Unpatched Vulnerability : CVE-2026-23953), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the databases at Tenable (296221) and EUVD (EUVD-2026-3804). Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• lxc

Name

• incus

Version

• 6.0
• 6.0.0
• 6.0.1
• 6.0.2
• 6.0.3
• 6.0.4
• 6.0.5
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6
• 6.7
• 6.8
• 6.9
• 6.10
• 6.11
• 6.12
• 6.13
• 6.14
• 6.15
• 6.16
• 6.17
• 6.18
• 6.19
• 6.20.0

Website

• Product: https://github.com/lxc/incus/

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