Drupal PECL YAML parser unsafe object handling
Drupal core 8 before versions 8.3.4 allows remote attackers to execute arbitrary code due to the PECL YAML parser not handling PHP objects safely during certain operations.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | drupal/core | >= 8.0, < 8.3.4 | 8.3.4 |
| Composer package | drupal/drupal | >= 8.0, < 8.3.4 | 8.3.4 |
| Drupal (core) | drupal/core | >= 8.0, < 8.3.4, >= 8.0, < 8.3.4 | 8.3.4 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2017-6920
- https://github.com/FriendsOfPHP/security-advisories/blob/master/drupal/core/CVE-2017-6920.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/drupal/drupal/CVE-2017-6920.yaml
- https://github.com/drupal/core
- https://www.drupal.org/SA-CORE-2017-003
- https://www.drupal.org/forum/newsletters/security-advisories-for-drupal-core/2017-06-21/drupal-core-multiple
- http://www.securityfocus.com/bid/99211
- http://www.securitytracker.com/id/1038781
- CVSS vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H- Weakness (CWE)
CWE-94- Platform
- Composer, Drupal
- Package
drupal/core, drupal/drupal- Disclosed
- 14.05.2022
- Updated
- 11.10.2026 11:18
Sources and licenses
OSV / GitHub Advisory Database - GHSA-9c24-g32g-35rj - CC BY 4.0
Vulnerability history: drupal/core
All published vulnerabilities of this package (Drupal (core)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 165
- First → latest
- 02.2018 09.2026
- Without a fix
- 3
- Exploited in attacks
- 5
Severity breakdown
- Critical 17
- High 44
- Medium 72
- Low 6
- Unrated 26
Disclosures per year
- 2018: 4
- 2019: 14
- 2020: 12
- 2021: 11
- 2022: 61
- 2023: 6
- 2024: 36
- 2025: 8
- 2026: 13
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