Vulnerability-Lookup

ubuntu-cve-2026-33711

Vulnerability from osv_ubuntu

Published

2026-03-26 23:16

Modified

2026-07-02 16:13

Summary

Details

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.

Severity

4.7 (Medium)


                    
                      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

7.8 (High)


                    
                      CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-33711	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-33711	REPORT
	https://github.com/lxc/incus/pull/3092	REPORT
	https://github.com/lxc/incus/security/advisories/…	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "golang-github-lxc-incus-dev",
            "binary_version": "6.0.0-1ubuntu0.3+esm3"
          },
          {
            "binary_name": "incus",
            "binary_version": "6.0.0-1ubuntu0.3+esm3"
          },
          {
            "binary_name": "incus-agent",
            "binary_version": "6.0.0-1ubuntu0.3+esm3"
          },
          {
            "binary_name": "incus-client",
            "binary_version": "6.0.0-1ubuntu0.3+esm3"
          },
          {
            "binary_name": "incus-migrate",
            "binary_version": "6.0.0-1ubuntu0.3+esm3"
          },
          {
            "binary_name": "incus-tools",
            "binary_version": "6.0.0-1ubuntu0.3+esm3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:24.04:LTS",
        "name": "incus",
        "purl": "pkg:deb/ubuntu/incus@6.0.0-1ubuntu0.3+esm3?arch=source\u0026distro=esm-apps/noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.4-1ubuntu1",
        "0.5.1-1",
        "0.5.1-3",
        "0.6-1",
        "6.0.0-1",
        "6.0.0-1ubuntu0.1",
        "6.0.0-1ubuntu0.2",
        "6.0.0-1ubuntu0.2+esm1",
        "6.0.0-1ubuntu0.3",
        "6.0.0-1ubuntu0.3+esm1",
        "6.0.0-1ubuntu0.3+esm2",
        "6.0.0-1ubuntu0.3+esm3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "golang-github-lxc-incus-dev",
            "binary_version": "6.0.4-2"
          },
          {
            "binary_name": "incus",
            "binary_version": "6.0.4-2"
          },
          {
            "binary_name": "incus-agent",
            "binary_version": "6.0.4-2"
          },
          {
            "binary_name": "incus-base",
            "binary_version": "6.0.4-2"
          },
          {
            "binary_name": "incus-client",
            "binary_version": "6.0.4-2"
          },
          {
            "binary_name": "incus-extra",
            "binary_version": "6.0.4-2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "incus",
        "purl": "pkg:deb/ubuntu/incus@6.0.4-2?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "6.0.3-4",
        "6.0.4-2"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "golang-github-lxc-incus-dev",
            "binary_version": "6.0.5-8ubuntu0.26.04.1~esm1"
          },
          {
            "binary_name": "incus",
            "binary_version": "6.0.5-8ubuntu0.26.04.1~esm1"
          },
          {
            "binary_name": "incus-agent",
            "binary_version": "6.0.5-8ubuntu0.26.04.1~esm1"
          },
          {
            "binary_name": "incus-base",
            "binary_version": "6.0.5-8ubuntu0.26.04.1~esm1"
          },
          {
            "binary_name": "incus-client",
            "binary_version": "6.0.5-8ubuntu0.26.04.1~esm1"
          },
          {
            "binary_name": "incus-extra",
            "binary_version": "6.0.5-8ubuntu0.26.04.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:26.04:LTS",
        "name": "incus",
        "purl": "pkg:deb/ubuntu/incus@6.0.5-8ubuntu0.26.04.1~esm1?arch=source\u0026distro=esm-apps/resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "6.0.4-2",
        "6.0.5-8",
        "6.0.5-8ubuntu0.26.04.1~esm1"
      ]
    }
  ],
  "aliases": [],
  "details": "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.",
  "id": "UBUNTU-CVE-2026-33711",
  "modified": "2026-07-02T16:13:28Z",
  "published": "2026-03-26T23:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-33711"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-33711"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/lxc/incus/pull/3092"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/lxc/incus/security/advisories/GHSA-q9vp-3wcg-8p4x"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    },
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-33711"
  ]
}

CVE-2026-33711 (GCVE-0-2026-33711)

Vulnerability from cvelistv5 – Published: 2026-03-26 22:37 – Updated: 2026-03-27 20:00

Title

Incus vulnerable to local privilege escalation through VM screenshot path

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.

Severity

4.7 (Medium)


                        
                          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

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-61 - UNIX Symbolic Link (Symlink) Following

Assigner

GitHub_M

References

1 reference

URL	Tags
https://github.com/lxc/incus/security/advisories/…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version
lxc	incus	Affected: < 6.23.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-33711",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-27T14:10:12.851754Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-27T20:00:18.358Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/lxc/incus/security/advisories/GHSA-q9vp-3wcg-8p4x"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "incus",
          "vendor": "lxc",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 6.23.0"
            }
          ]
        }
      ],
      "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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "LOCAL",
            "baseScore": 4.7,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "LOW",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "HIGH"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-61",
              "description": "CWE-61: UNIX Symbolic Link (Symlink) Following",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-26T22:37:29.746Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/lxc/incus/security/advisories/GHSA-q9vp-3wcg-8p4x",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/lxc/incus/security/advisories/GHSA-q9vp-3wcg-8p4x"
        }
      ],
      "source": {
        "advisory": "GHSA-q9vp-3wcg-8p4x",
        "discovery": "UNKNOWN"
      },
      "title": "Incus vulnerable to local privilege escalation through VM screenshot path"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-33711",
    "datePublished": "2026-03-26T22:37:29.746Z",
    "dateReserved": "2026-03-23T17:06:05.747Z",
    "dateUpdated": "2026-03-27T20:00:18.358Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

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.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

ubuntu-cve-2026-33711

Vulnerability from osv_ubuntu

CVE-2026-33711 (GCVE-0-2026-33711)

Tags

Sightings

Nomenclature