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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Apache Software Foundation | Apache BuildStream | ≤ 2.8.0 | 2.8.1 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | buildstream | 2.8.1-1 | — |
| Debian 13 | buildstream | 1.6.9-2+deb13u1 | — |
| Debian 12 | buildstream | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | buildstream | No fix yet | — |
| Ubuntu 24.04 LTS | buildstream | No fix yet | — |
| Ubuntu 22.04 LTS | buildstream | No fix yet | — |
| Ubuntu 20.04 LTS | buildstream | No fix yet | — |
References
- https://lists.apache.org/thread/9b342631x7bvtyg0pq7zgywtl2cmy34v vendor-advisory