CVE-2026-23953

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{"affected": [{"affectedData": [{"product": "incus", "vendor": "lxc", "versions": [{"status": "affected", "version": ">= 6.1.0, <= 6.20.0"}, {"status": "affected", "version": "<= 6.0.5"}]}], "source": "security-advisories@github.com"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:linuxcontainers:incus:*:*:*:*:*:*:*:*", "matchCriteriaId": "0DF87DBE-86FF-4E74-8086-AE3360A94C71", "versionEndIncluding": "6.0.5", "vulnerable": true}, {"criteria": "cpe:2.3:a:linuxcontainers:incus:*:*:*:*:*:*:*:*", "matchCriteriaId": "47AA575C-385C-4C34-8CC0-F370EC4ED7B4", "versionEndExcluding": "6.21.0", "versionStartIncluding": "6.1.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "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 \u2018incus\u2019 group) can create an environment variable containing newlines, which can be used to add additional configuration items in the container\u2019s 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\nand 6.21.0, but they have not been released at the time of publication."}, {"lang": "es", "value": "Incus es un gestor de contenedores de sistema y m\u00e1quinas virtuales. En las versiones 6.20.0 e inferiores, un usuario con la capacidad de lanzar un contenedor con una configuraci\u00f3n YAML personalizada (por ejemplo, un miembro del grupo 'incus') puede crear una variable de entorno que contiene saltos de l\u00ednea, la cual puede usarse para a\u00f1adir elementos de configuraci\u00f3n adicionales en el lxc.conf del contenedor debido a la inyecci\u00f3n de saltos de l\u00ednea. Esto puede permitir a\u00f1adir ganchos de ciclo de vida arbitrarios, lo que en \u00faltima instancia resulta en la ejecuci\u00f3n arbitraria de comandos en el anfitri\u00f3n. Explotar este problema en IncusOS requiere una ligera modificaci\u00f3n de la carga \u00fatil para cambiar a un directorio diferente con permisos de escritura para el paso de validaci\u00f3n (por ejemplo, /tmp). Esto puede confirmarse con un segundo contenedor con /tmp montado desde el anfitri\u00f3n (Una acci\u00f3n privilegiada solo para validaci\u00f3n). Se planea una soluci\u00f3n para las versiones 6.0.6 y 6.21.0, pero no han sido lanzadas en el momento de la publicaci\u00f3n."}], "id": "CVE-2026-23953", "lastModified": "2026-06-17T10:22:20.643", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "ADJACENT_NETWORK", "availabilityImpact": "NONE", "baseScore": 8.7, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 2.3, "impactScore": 5.8, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-23953", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-01-26T21:00:32.625486Z", "version": "2.0.3"}}]}, "published": "2026-01-22T22:16:20.673", "references": [{"source": "security-advisories@github.com", "tags": ["Product"], "url": "https://github.com/lxc/incus/blob/HEAD/internal/server/instance/drivers/driver_lxc.go#L1081"}, {"source": "security-advisories@github.com", "tags": ["Exploit", "Vendor Advisory"], "url": "https://github.com/lxc/incus/security/advisories/GHSA-x6jc-phwx-hp32"}, {"source": "security-advisories@github.com", "tags": ["Exploit"], "url": "https://github.com/user-attachments/files/24473682/environment_newline_injection.sh"}, {"source": "security-advisories@github.com", "tags": ["Patch"], "url": "https://github.com/user-attachments/files/24473685/environment_newline_injection.patch"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-93"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

{}

{"analysis": {"en": {"generated_at": "2026-04-18T03:36:22.413457+00:00", "value": {"mitigation_remediation": ["Upgrade to a release newer than 6.21.0 that includes the official newline\u2011injection patch.", "If upgrading is not possible, remove non\u2011privileged users from the incus group or restrict group membership to trusted administrators.", "Disable or sanitize custom YAML configuration that allows environment variables containing newlines, for example by enforcing a policy that rejects such values or limiting the use of environment variables to single\u2011line values.", "As an interim workaround, apply the community patch available at https://github.com/user-attachments/files/24473685/environment_newline_injection.patch and subsequently exclude impacted containers from host filesystem mounts like /tmp."], "summary": {"action": "Apply Patch", "impact": "Local Privilege Escalation"}, "threat_synthesis": {"affected_systems": "The flaw exists in Incus version 6.20.0 and earlier. Users who belong to the incus group or have permission to create containers with custom YAML files can trigger the injection. The planned fix is slated for releases 6.0.6 and 6.21.0, which have not yet been made publicly available.", "description_and_impact": "The vulnerability arises from newline injection in environment variable handling during container initialization. An attacker who can launch a container through a custom YAML configuration can embed newline characters in an environment variable value, causing the Incus engine to split the value into multiple configuration directives. This effectively allows the insertion of arbitrary lifecycle hooks into the container\u2019s LXC configuration. The injected hooks can execute arbitrary code on the host, leading to full host control and representing a severe Local Privilege Escalation flaw. This weakness is identified as CWE\u201193.", "risk_and_exploitability": "The CVSS base score is 8.7, indicating high severity, while the EPSS score of less than 1% suggests a low current exploitation probability. The vulnerability is not listed in the CISA KEV catalog. Since exploitation requires only local access to the Incus management interface and membership in the incus group, it does not depend on network exposure. An attacker can validate the payload by mounting /tmp from the host, a privileged operation reserved for validation steps. The attack surface is therefore limited to users with container creation permissions, and no known active exploitation has been reported."}}}}, "created": "2026-01-23T10:27:09.796843+00:00", "updated": "2026-04-18T03:45:21.073512+00:00", "vendors": ["lxc", "lxc$PRODUCT$incus"]}