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CVE-2026-82331

9.8 · CRITICAL

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 file…

Published Sep 23, 2026CWE-59EPSS 0.41%

Overview

CVE-2026-82331 is a critical-severity vulnerability. It was published on September 23, 2026 and has a CVSS 3.1 base score of 9.8 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Reflists.apache.org/thread/9b342631x7bvtyg0pq7zgywtl2cmy34vRefwww.openwall.com/lists/oss-security/2026/09/23/9

How CyberStrike helps

Frequently asked questions

What is CVE-2026-82331?

CVE-2026-82331 is a critical-severity vulnerability. It was published on September 23, 2026 and has a CVSS 3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-82331?

This vulnerability has a CVSS 3.1 base score of 9.8, rated CRITICAL. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-82331?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-82331?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-82331 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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