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. 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
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Users are recommended to upgrade to version 2.8.1, which fixes this issue.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 9.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.42%
- Percentil entre todas las CVEs puntuadas: 35
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1190Exploit Public-Facing Applicationinitial access75 % - Impacto principal
T1565.001Stored Data Manipulationimpact85 %
Vulnerabilidad de link following (CWE-59) en plugin tar de BuildStream permite escribir archivos maliciosos mediante symlinks en tarballs durante la descarga de fuentes (T1190). El atacante logra manipulación de datos (T1565.001) y potencial escalada de privilegios (T1068) con los permisos del usuar
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
CWE
- CWE-59
Referencias
JSON original (NVD)
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"timestamp": "2026-09-23T14:55:37.367789Z"
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"affected": [
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"source": "security@apache.org",
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"published": "2026-09-23T07:16:46.493",
"references": [
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"value": "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\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\n\nUsers are recommended to upgrade to version 2.8.1, which fixes this issue."
}
],
"lastModified": "2026-09-23T17:58:26.570",
"sourceIdentifier": "security@apache.org"
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