Vulnerability-Lookup

UBUNTU-CVE-2026-82331 (CVE-2026-82331)

Vulnerability from osv_ubuntu – Published: 2026-09-23 07:16 – Updated: 2026-09-23 07:16 – Source website

Details

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.

Severity

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-82331	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-82331	REPORT
	https://lists.apache.org/thread/9b342631x7bvtyg0p…	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "buildstream",
            "binary_version": "1.4.1-1"
          },
          {
            "binary_name": "python3-buildstream",
            "binary_version": "1.4.1-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "buildstream",
        "purl": "pkg:deb/ubuntu/buildstream@1.4.1-1?arch=source\u0026distro=focal"
      },
      "ranges": [
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          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.4.1-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "buildstream",
            "binary_version": "1.6.1-1"
          },
          {
            "binary_name": "python3-buildstream",
            "binary_version": "1.6.1-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "buildstream",
        "purl": "pkg:deb/ubuntu/buildstream@1.6.1-1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.6.1-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "buildstream",
            "binary_version": "1.6.9-1"
          },
          {
            "binary_name": "python3-buildstream",
            "binary_version": "1.6.9-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "buildstream",
        "purl": "pkg:deb/ubuntu/buildstream@1.6.9-1?arch=source\u0026distro=noble"
      },
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        {
          "events": [
            {
              "introduced": "0"
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          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "1.6.9-1"
      ]
    }
  ],
  "aliases": [],
  "details": "Improper link resolution before file access (\u0027link following\u0027) vulnerability in the `tar` source plugin of Apache BuildStream running on Python \u003c 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 \u003e= 3.12, BuildStream \u003e= 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.",
  "id": "UBUNTU-CVE-2026-82331",
  "modified": "2026-09-23T07:16:00Z",
  "published": "2026-09-23T07:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-82331"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-82331"
    },
    {
      "type": "REPORT",
      "url": "https://lists.apache.org/thread/9b342631x7bvtyg0pq7zgywtl2cmy34v"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-82331"
  ]
}

CVE-2026-82331 (GCVE-0-2026-82331)

Vulnerability from cvelistv5 – Published: 2026-09-23 06:58 – Updated: 2026-09-23 16:08

Title

Apache BuildStream: tar source extraction escape

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.

Severity

9.8 (Critical)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-23 14:55 UTC

CWE

CWE-59 - Improper link resolution before file access ('link following')

Assigner

apache mitre root

References

2 references

URL	Tags
https://lists.apache.org/thread/9b342631x7bvtyg0p…	vendor-advisory
http://www.openwall.com/lists/oss-security/2026/09/23/9

Impacted products

1 product

Vendor	Product	Version
Apache Software Foundation	Apache BuildStream	Affected: 0 , ≤ 2.8.0 (semver) Unaffected: 2.8.1 (semver)

Credits

Gjoko Krstic of Zero Science Lab

Show details on NVD website

JSON

To clipboard

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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.

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.
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UBUNTU-CVE-2026-82331 (CVE-2026-82331)

CVE-2026-82331 (GCVE-0-2026-82331)

Tags

Sightings

Nomenclature

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