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{"bugzilla": {"description": "buildstream: Apache BuildStream: Arbitrary file write via symlinks in tar source plugin", "id": "2539099", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2539099"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.6", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:H", "status": "draft"}, "cwe": "CWE-59", "details": ["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.\nThe impact of this issue is mitigated by:\n* BuildStream projects should only use trusted sources in their elements as otherwise the build output can also not be trusted\n* Tracking a source tarball pins its SHA256 hash, which prevents MITM attacks of users that are fetching an already tracked project\n* When running on Python >= 3.12, BuildStream >= 2.3.0 already makes use of the Python `tarfile` filter functionality, which blocks the symlink escape\nUsers are recommended to upgrade to version 2.8.1, which fixes this issue.", "A flaw was found in the `tar` source plugin of Apache BuildStream. This improper link resolution vulnerability, also known as 'link following', allows a remote attacker to write arbitrary files on the host system. By crafting malicious source tarballs containing symlinks, an attacker can exploit this flaw during source fetching to execute code or escalate privileges with the permissions of the user running BuildStream."], "name": "CVE-2026-82331", "public_date": "2026-09-23T06:58:21Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-82331\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-82331\nhttps://lists.apache.org/thread/9b342631x7bvtyg0pq7zgywtl2cmy34v"], "statement": "This vulnerability is assessed as Moderate severity because exploitation requires a user to explicitly fetch an untrusted archive, and any resultant file modification remains strictly confined to the access permissions of the invoking account. Apache BuildStream is not included or supported in Red Hat Enterprise Linux, limiting exposure to community distributions. Additionally, environments executing on Python 3.12 or newer inherently prevent this directory traversal through native archive extraction filters.", "threat_severity": "Moderate"}