Advisory severityCritical9.8Apache Software Foundation

Critical [CVE-2026-82331] 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

This critical-severity Apache Software Foundation advisory covers CVE-2026-82331 affecting Apache BuildStream.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-82331 Source published Sep 23, 2026Source updated Sep 23, 2026

VulniPulse record published Sep 23, 2026Record updated Sep 23, 2026

CVE-2026-82331

Affected products & platforms

Apache Software FoundationUnclassified

Open source advisory

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Summary

Improper link resolution before file access ('link following') vulnerability in the `tar` source plugin of Apache BuildStream 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.

Affected versions

Apache BuildStream through 2.8.0

Official advisory · high-confidence parse· fetched 13 days ago·verify at source

Fixed versions

2.8.1

Official advisory · high-confidence parse· fetched 13 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation

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.

Official advisory · high-confidence parse· fetched 13 days ago·verify at source

Sources

Official and corroborating records used to build this advisory.

Official vendor advisoryofficial
Official advisory page fetched and parsed; accepted detail fields are attributed to this page.
Apache Software Foundation
CVE.org CNA recordCVE.org
Independent CNA record used for near-real-time discovery and missed-CVE reconciliation. Discovered from the machine-readable feed https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/delta.json; this link opens the CVE.org record for CVE-2026-82331 instead of the raw feed document.
CVE Program

Cross-references

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CVE-2026-82331NVD CVE.org MITRE

Official resources

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Apache project downloads (fixed releases)
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