CVE-2021-34551: Malicious File Upload
First published: Wed Jun 16 2021(Updated: )
PHPMailer 6.4.1 contains a possible remote code execution vulnerability through the `$lang_path` parameter of the `setLanguage()` method. If the `$lang_path` parameter is passed unfiltered from user input, it can be set to [a UNC path](https://docs.microsoft.com/en-us/dotnet/standard/io/file-path-formats#unc-paths), and if an attacker is also able to create a remote mount on the server that the UNC path points to, a script file under their control may be executed. ### Impact Arbitrary code may be run by a remote attacker under the web server or PHP process running on Window hosts. ### Patches Mitigated in PHPMailer 6.5.0 by no longer treating translation files as PHP code, but by parsing their text content directly. This approach avoids the possibility of executing unknown code while retaining backward compatibility. This isn't ideal, so the current translation format is deprecated and will be replaced in the next major release. ### Workarounds Any of: * Ensure that calling code does not pass unfiltered user-supplied data to the `$lang_path` parameter of the `setLanguage()` method. * Block or filter the use of unknown UNC paths in this parameter (or altogether). * Ensure that unauthorised users do not have the ability to read from unknown remote servers via UNC paths. * Run on an OS that does not support UNC paths ### References [CVE-2021-34551](https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-34551). Reported by [listensec.com](https://listensec.com) via Tidelift. ### For more information If you have any questions or comments about this advisory: * Open an issue in [PHPMailer](https://github.com/PHPMailer/PHPMailer) * [Email the maintainers](mailto:phpmailer@synchromedia.co.uk)
Credit: cve@mitre.org cve@mitre.org
| Affected Software | Affected Version | How to fix |
|---|---|---|
| composer/phpmailer/phpmailer | <6.5.0 | 6.5.0 |
| Phpmailer Project Phpmailer | <6.5.0 | |
| Microsoft Windows | ||
| Fedoraproject Fedora | =33 | |
| Fedoraproject Fedora | =34 | |
| composer/phpmailer/phpmailer | <6.5.0 | 6.5.0 |
| All of | ||
| Phpmailer Project Phpmailer | <6.5.0 | |
| Microsoft Windows |
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Reference Links
- https://github.com/PHPMailer/PHPMailer/releases/tag/v6.5.0
- https://github.com/PHPMailer/PHPMailer/blob/master/SECURITY.md
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3YRMWGA4VTMXFB22KICMB7YMFZNFV3EJ/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/FJYSOFCUBS67J3TKR74SD3C454N7VTYM/
- https://github.com/PHPMailer/PHPMailer/security/advisories/GHSA-7q44-r25x-wm4q
- https://nvd.nist.gov/vuln/detail/CVE-2021-34551
- https://github.com/PHPMailer/PHPMailer/commit/acd264bf17ff4ac5c915f0d4226dce8a9ea70bc3
- https://github.com/FriendsOfPHP/security-advisories/blob/master/phpmailer/phpmailer/CVE-2021-34551.yaml
- https://github.com/advisories/GHSA-7q44-r25x-wm4q (Advisory)
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3YRMWGA4VTMXFB22KICMB7YMFZNFV3EJ/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FJYSOFCUBS67J3TKR74SD3C454N7VTYM/
Frequently Asked Questions
What is CVE-2021-34551?
CVE-2021-34551 is a vulnerability that allows remote code execution on Windows hosts using PHPMailer before version 6.5.0.
How does CVE-2021-34551 affect Windows hosts?
CVE-2021-34551 allows remote code execution on Windows hosts if the 'lang_path' parameter is untrusted data and contains a UNC pathname.
What is the severity of CVE-2021-34551?
The severity of CVE-2021-34551 is high, with a CVSS score of 8.1.
How can I fix CVE-2021-34551?
To fix CVE-2021-34551, you should update PHPMailer to version 6.5.0 or higher.
Where can I find more information about CVE-2021-34551?
More information about CVE-2021-34551 can be found on the GitHub releases page of PHPMailer (v6.5.0) and the security documentation in the repository.
- collector/friends-of-php
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- agent/type
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- source/GitHub
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- alias/CVE-2021-34551
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- vendor/microsoft
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- version/fedoraproject fedora/33
- version/fedoraproject fedora/34