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VulnerabilityPublished

CVE-2026-82331: Apache BuildStream · Link Following

Affects Apache BuildStreamSource CVE Database V5

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Not known to be exploited · CVSS 9.8 Critical · fixed in 2.8.1 : patch Apache BuildStream as a priority.

Data as of 6 Nov 2026, 23:24 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 35% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 2.8.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 23 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Apache Software FoundationApache BuildStreamAffected
  • <=2.8.0
Fixed in–
PyPIbuildstreampkg:pypi/buildstreamOther threatsAffected
  • <=2.8.0
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Users should upgrade Apache BuildStream to version 2.8.1, which fixes this vulnerability. Additionally, ensure that only trusted sources are used in BuildStream projects and that source tarballs are tracked with pinned SHA256 hashes to prevent MITM attacks. Running BuildStream on Python 3.12 or later with BuildStream 2.3.0 or later also mitigates this issue by blocking symlink escapes via the Python tarfile filter functionality.

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.

References

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