Description
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.
Published: 2026-09-23
Score: n/a
EPSS: n/a
KEV: No
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Remediation

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Tracking

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Advisories

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History

Wed, 23 Sep 2026 11:45:00 +0000

Type Values Removed Values Added
Description 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.
Title Apache BuildStream: tar source extraction escape
Weaknesses CWE-59
References

Subscriptions

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cve-icon MITRE

Status: PUBLISHED

Assigner: apache

Published:

Updated: 2026-09-23T06:58:21.546Z

Reserved: 2026-08-28T14:59:00.996Z

Link: CVE-2026-82331

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-23T07:16:46.493

Modified: 2026-09-23T07:16:46.493

Link: CVE-2026-82331

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses
  • CWE-59

    Improper Link Resolution Before File Access ('Link Following')