Vulnerability-Lookup

ubuntu-cve-2026-63343

Vulnerability from osv_ubuntu

Published

2026-08-21 15:16

Modified

2026-09-02 16:20

Summary

Details

Incus is a system container and virtual machine manager. Prior to version 7.3.0, a malicious image containing a metadata.yaml symlink pointing to an arbitrary host path allows an authenticated Incus user to read or overwrite any file on the host as root via the instance metadata API. The exec-output and templates/ paths were patched in a prior release using Lstat rejection and os.OpenRoot confinement; metadata.yaml was not included in either patch and remains exploitable. Version 7.3.0 patches the issue.

Severity

9.9 (Critical)


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

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-63343	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-63343	REPORT
	https://github.com/lxc/incus/security/advisories/…	REPORT
	https://github.com/lxc/incus/pull/3750	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": "6.0.5-8ubuntu0.26.04.1~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. Prior to version 7.3.0, a malicious image containing a `metadata.yaml` symlink pointing to an arbitrary host path allows an authenticated Incus user to read or overwrite any file on the host as root via the instance metadata API. The `exec-output` and `templates/` paths were patched in a prior release using `Lstat` rejection and `os.OpenRoot` confinement; `metadata.yaml` was not included in either patch and remains exploitable. Version 7.3.0 patches the issue.",
  "id": "UBUNTU-CVE-2026-63343",
  "modified": "2026-09-02T16:20:06Z",
  "published": "2026-08-21T15:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-63343"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-63343"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/lxc/incus/security/advisories/GHSA-fmjx-5j3g-997p"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/lxc/incus/pull/3750"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-63343"
  ]
}

CVE-2026-63343 (GCVE-0-2026-63343)

Vulnerability from cvelistv5 – Published: 2026-08-21 14:53 – Updated: 2026-08-21 21:44

Title

Arbitrary File Read/Write: metadata.yaml symlink in image allows host filesystem access as root

Summary

Incus is a system container and virtual machine manager. Prior to version 7.3.0, a malicious image containing a `metadata.yaml` symlink pointing to an arbitrary host path allows an authenticated Incus user to read or overwrite any file on the host as root via the instance metadata API. The `exec-output` and `templates/` paths were patched in a prior release using `Lstat` rejection and `os.OpenRoot` confinement; `metadata.yaml` was not included in either patch and remains exploitable. Version 7.3.0 patches the issue.

Severity

9.9 (Critical)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-21 21:00 UTC

CWE

CWE-73 - External Control of File Name or Path

Assigner

GitHub_M mitre root

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: < 7.3.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-63343",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-21T21:00:14.696240Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-21T21:44:03.623Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "incus",
          "vendor": "lxc",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 7.3.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Incus is a system container and virtual machine manager. Prior to version 7.3.0, a malicious image containing a `metadata.yaml` symlink pointing to an arbitrary host path allows an authenticated Incus user to read or overwrite any file on the host as root via the instance metadata API. The `exec-output` and `templates/` paths were patched in a prior release using `Lstat` rejection and `os.OpenRoot` confinement; `metadata.yaml` was not included in either patch and remains exploitable. Version 7.3.0 patches the issue."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 9.9,
            "baseSeverity": "CRITICAL",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "LOW",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-73",
              "description": "CWE-73: External Control of File Name or Path",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-21T14:53:26.109Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/lxc/incus/security/advisories/GHSA-fmjx-5j3g-997p",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/lxc/incus/security/advisories/GHSA-fmjx-5j3g-997p"
        }
      ],
      "source": {
        "advisory": "GHSA-fmjx-5j3g-997p",
        "discovery": "UNKNOWN"
      },
      "title": "Arbitrary File Read/Write: metadata.yaml symlink in image allows host filesystem access as root"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-63343",
    "datePublished": "2026-08-21T14:53:26.109Z",
    "dateReserved": "2026-07-16T14:14:24.385Z",
    "dateUpdated": "2026-08-21T21:44:03.623Z",
    "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.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.