FKIE_CVE-2026-33711
Vulnerability from fkie_nvd - Published: 2026-03-26 23:16 - Updated: 2026-03-30 18:51
Severity ?
Summary
Incus is a system container and virtual machine manager. Incus provides an API to retrieve VM screenshots. That API relies on the use of a temporary file for QEMU to write the screenshot to which is then picked up and sent to the user prior to deletion. As versions prior to 6.23.0 use predictable paths under /tmp for this, an attacker with local access to the system can abuse this mechanism by creating their own symlinks ahead of time. On the vast majority of Linux systems, this will result in a "Permission denied" error when requesting a screenshot. That's because the Linux kernel has a security feature designed to block such attacks, `protected_symlinks`. On the rare systems with this purposefully disabled, it's then possible to trick Incus intro truncating and altering the mode and permissions of arbitrary files on the filesystem, leading to a potential denial of service or possible local privilege escalation. Version 6.23.0 fixes the issue.
References
| URL | Tags | ||
|---|---|---|---|
| security-advisories@github.com | https://github.com/lxc/incus/security/advisories/GHSA-q9vp-3wcg-8p4x | Exploit, Vendor Advisory | |
| 134c704f-9b21-4f2e-91b3-4a467353bcc0 | https://github.com/lxc/incus/security/advisories/GHSA-q9vp-3wcg-8p4x | Exploit, Vendor Advisory |
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| linuxcontainers | incus | * |
{
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:linuxcontainers:incus:*:*:*:*:*:*:*:*",
"matchCriteriaId": "CBE3ABCB-1D47-4A45-A09A-C9F609C53131",
"versionEndExcluding": "6.23.0",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
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]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Incus is a system container and virtual machine manager. Incus provides an API to retrieve VM screenshots. That API relies on the use of a temporary file for QEMU to write the screenshot to which is then picked up and sent to the user prior to deletion. As versions prior to 6.23.0 use predictable paths under /tmp for this, an attacker with local access to the system can abuse this mechanism by creating their own symlinks ahead of time. On the vast majority of Linux systems, this will result in a \"Permission denied\" error when requesting a screenshot. That\u0027s because the Linux kernel has a security feature designed to block such attacks, `protected_symlinks`. On the rare systems with this purposefully disabled, it\u0027s then possible to trick Incus intro truncating and altering the mode and permissions of arbitrary files on the filesystem, leading to a potential denial of service or possible local privilege escalation. Version 6.23.0 fixes the issue."
},
{
"lang": "es",
"value": "Incus es un gestor de contenedores de sistema y m\u00e1quinas virtuales. Incus proporciona una API para recuperar capturas de pantalla de la m\u00e1quina virtual. Esa API se basa en el uso de un archivo temporal para que QEMU escriba la captura de pantalla, la cual luego se recoge y se env\u00eda al usuario antes de su eliminaci\u00f3n. Dado que las versiones anteriores a la 6.23.0 utilizan rutas predecibles bajo /tmp para esto, un atacante con acceso local al sistema puede abusar de este mecanismo creando sus propios enlaces simb\u00f3licos con antelaci\u00f3n. En la gran mayor\u00eda de los sistemas Linux, esto resultar\u00e1 en un error de \u0027Permiso denegado\u0027 al solicitar una captura de pantalla. Esto se debe a que el kernel de Linux tiene una caracter\u00edstica de seguridad dise\u00f1ada para bloquear tales ataques, protected_symlinks. En los sistemas raros con esto deshabilitado a prop\u00f3sito, es entonces posible enga\u00f1ar a Incus para que trunque y altere el modo y los permisos de archivos arbitrarios en el sistema de archivos, lo que lleva a una potencial denegaci\u00f3n de servicio o posible escalada de privilegios local. La versi\u00f3n 6.23.0 corrige el problema."
}
],
"id": "CVE-2026-33711",
"lastModified": "2026-03-30T18:51:41.500",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9,
"source": "nvd@nist.gov",
"type": "Primary"
}
],
"cvssMetricV40": [
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"cvssData": {
"Automatable": "NOT_DEFINED",
"Recovery": "NOT_DEFINED",
"Safety": "NOT_DEFINED",
"attackComplexity": "LOW",
"attackRequirements": "PRESENT",
"attackVector": "LOCAL",
"availabilityRequirement": "NOT_DEFINED",
"baseScore": 4.7,
"baseSeverity": "MEDIUM",
"confidentialityRequirement": "NOT_DEFINED",
"exploitMaturity": "PROOF_OF_CONCEPT",
"integrityRequirement": "NOT_DEFINED",
"modifiedAttackComplexity": "NOT_DEFINED",
"modifiedAttackRequirements": "NOT_DEFINED",
"modifiedAttackVector": "NOT_DEFINED",
"modifiedPrivilegesRequired": "NOT_DEFINED",
"modifiedSubAvailabilityImpact": "NOT_DEFINED",
"modifiedSubConfidentialityImpact": "NOT_DEFINED",
"modifiedSubIntegrityImpact": "NOT_DEFINED",
"modifiedUserInteraction": "NOT_DEFINED",
"modifiedVulnAvailabilityImpact": "NOT_DEFINED",
"modifiedVulnConfidentialityImpact": "NOT_DEFINED",
"modifiedVulnIntegrityImpact": "NOT_DEFINED",
"privilegesRequired": "LOW",
"providerUrgency": "NOT_DEFINED",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"valueDensity": "NOT_DEFINED",
"vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"version": "4.0",
"vulnAvailabilityImpact": "NONE",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "HIGH",
"vulnerabilityResponseEffort": "NOT_DEFINED"
},
"source": "security-advisories@github.com",
"type": "Secondary"
}
]
},
"published": "2026-03-26T23:16:20.423",
"references": [
{
"source": "security-advisories@github.com",
"tags": [
"Exploit",
"Vendor Advisory"
],
"url": "https://github.com/lxc/incus/security/advisories/GHSA-q9vp-3wcg-8p4x"
},
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"tags": [
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"url": "https://github.com/lxc/incus/security/advisories/GHSA-q9vp-3wcg-8p4x"
}
],
"sourceIdentifier": "security-advisories@github.com",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-61"
}
],
"source": "security-advisories@github.com",
"type": "Secondary"
}
]
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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