buildstream — security advisory

{
  "id": "b25c9b7078dc37713c76a851877414645b88dd2fac622e16bca0147ed092fd22",
  "url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-82331",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "UBUNTU-CVE-2026-82331",
    "summary": "Improper link resolution before file access ('link following') vulnerability in the `tar` source plugin of Apache BuildStream running on Python < 3.12 allows malicious source tarballs to write files on the host, with the privileges of the user running BuildStream, via symlinks as part of source fetching. The impact of this issue is mitigated by: * BuildStream projects should only use trusted sources in their elements as otherwise the build output can also not be trusted * Tracking a source tarball pins its SHA256 hash, which prevents MITM attacks of users that are fetching an already tracked project * When running on Python >= 3.12, BuildStream >= 2.3.0 already makes use of the Python `tarfile` filter functionality, which blocks the symlink escape Users are recommended to upgrade to version 2.8.1, which fixes this issue.",
    "evidence": "osv:UBUNTU-CVE-2026-82331",
    "products": [
      {
        "name": {
          "value": "buildstream",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.4.1-1",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "buildstream",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.6.1-1",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "buildstream",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.6.9-1",
            "evidence": "/affected/2/versions"
          }
        ]
      },
      {
        "name": {
          "value": "buildstream",
          "evidence": "/affected/3/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "2.7.0-3",
            "evidence": "/affected/3/versions"
          },
          {
            "value": "2.8.0-1",
            "evidence": "/affected/3/versions"
          },
          {
            "value": "2.8.1-1",
            "evidence": "/affected/3/versions"
          }
        ]
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "UBUNTU-CVE-2026-82331",
      "aliases": [
        "UBUNTU-CVE-2026-82331"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
        },
        {
          "type": "Ubuntu",
          "score": "medium"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "buildstream",
            "purl": "pkg:deb/ubuntu/buildstream?arch=source&distro=focal",
            "ecosystem": "Ubuntu:20.04:LTS"
          },
          "versions": [
            "1.4.1-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-82331.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "buildstream",
                "binary_version": "1.4.1-1"
              },
              {
                "binary_name": "python3-buildstream",
                "binary_version": "1.4.1-1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "buildstream",
            "purl": "pkg:deb/ubuntu/buildstream?arch=source&distro=jammy",
            "ecosystem": "Ubuntu:22.04:LTS"
          },
          "versions": [
            "1.6.1-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-82331.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "buildstream",
                "binary_version": "1.6.1-1"
              },
              {
                "binary_name": "python3-buildstream",
                "binary_version": "1.6.1-1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "buildstream",
            "purl": "pkg:deb/ubuntu/buildstream?arch=source&distro=noble",
            "ecosystem": "Ubuntu:24.04:LTS"
          },
          "versions": [
            "1.6.9-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-82331.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "buildstream",
                "binary_version": "1.6.9-1"
              },
              {
                "binary_name": "python3-buildstream",
                "binary_version": "1.6.9-1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "buildstream",
            "purl": "pkg:deb/ubuntu/buildstream?arch=source&distro=stonking",
            "ecosystem": "Ubuntu:26.10"
          },
          "versions": [
            "2.7.0-3",
            "2.8.0-1",
            "2.8.1-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-82331.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "buildstream",
                "binary_version": "2.8.1-1"
              },
              {
                "binary_name": "python3-buildstream",
                "binary_version": "2.8.1-1"
              }
            ]
          }
        }
      ],
      "modified": "2026-10-17T13:01:11.003869160Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-82331"
      ],
      "references": [
        "https://ubuntu.com/security/CVE-2026-82331",
        "https://www.cve.org/CVERecord?id=CVE-2026-82331",
        "https://lists.apache.org/thread/9b342631x7bvtyg0pq7zgywtl2cmy34v"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-82331",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 361155,
  "published_at": "2026-09-23T07:16:00+00:00"
}