CVE-2026-23953 | Incus container environment configuration newline injection

Exp

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.

Published: 2026-01-22 Last update: 2026-01-30 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2026-23953 is rated Exploit Available (50.2/100): CVSS High severity, with low exploitation likelihood (EPSS 0.01%). Core evidence: 2 public exploit reference(s) are indexed (Exploit-DB). Mandatory action: Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-23953

EDB-ID Source Kind Published Link
nvd_ref exploit_tag Exploit-DB ↗
nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-23953

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-01-23 0.01%

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-23953

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.7 3.1 HIGH
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
2.3 5.8 [email protected]

Weakness enumeration for CVE-2026-23953

GitHub Security Advisory for CVE-2026-23953

GHSA-x6jc-phwx-hp32 · Severity: high · Ecosystem: go — Incus container environment configuration newline injection

OS Trackers for CVE-2026-23953

vendor priority summary link
alpine CVE-2026-23953: 2 source package rows (incus, incus-feature); 29 state rows across 2 repos (3.23-community, edge-community); fixed 9, open 20. https://security.alpinelinux.org/vuln/CVE-2026-23953
debian not yet assigned CVE-2026-23953 not yet assigned priority: Debian including 2 source packages (incus, lxd), 5 status rows across 4 suites (bookworm, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2026-23953
ubuntu medium CVE-2026-23953 medium priority: Ubuntu including 2 source packages (incus, lxd), 11 status rows across 7 suites (bionic, focal, jammy, noble, questing, upstream, xenial): needs-triage 6, DNE 4, released 1. https://ubuntu.com/security/CVE-2026-23953

Affected software / configurations for CVE-2026-23953

Vendor Product Version Raw CPE
linuxcontainers incus <= 6.0.5 cpe:2.3:a:linuxcontainers:incus:*:*:*:*:*:*:*:*
linuxcontainers incus >= 6.1.0, < 6.21.0 cpe:2.3:a:linuxcontainers:incus:*:*:*:*:*:*:*:*

References for CVE-2026-23953

cvelogic Threat Intelligence