CVE-2026-82331
CRITICALDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 35% of all known CVEs.
References
Related Vulnerabilities
Other CWE-59 (Link Following) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2022-30333 | High | 7.5 | 99% | KEV + Ransom | Fix |
| CVE-2021-21300 | High | 8.0 | 89% | - | Fix |
| CVE-2021-32610 | High | 7.1 | 73% | - | Fix |
| CVE-2020-36193 | High | 7.5 | 71% | KEV | Fix |
| CVE-2023-40028 | Medium | 4.9 | 69% | - | Fix |
| CVE-2024-57728 | High | 7.2 | 65% | KEV + Ransom | Fix |
Common questions
How do I fix CVE-2026-82331?
Upgrade buildstream on debian unstable to 2.8.1-1 or later.
Is CVE-2026-82331 being actively exploited?
Not that we know of. CVE-2026-82331 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.42% is the estimated probability that it will be exploited in the next 30 days. That is higher than 35% of all scored CVEs.
How severe is CVE-2026-82331?
CVE-2026-82331 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-82331 affect?
Published advisories record a fix for buildstream (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-23.