Summary
Local file disclosure in PHPMailer
An issue was discovered in PHPMailer before 5.2.22. PHPMailer's msgHTML method applies transformations to an HTML document to make it usable as an email message body. One of the transformations is to convert relative image URLs into attachments using a script-provided base directory. If no base directory is provided, it resolves to /, meaning that relative image URLs get treated as absolute local file paths and added as attachments. To form a remote vulnerability, the msgHTML method must be called, passed an unfiltered, user-supplied HTML document, and must not set a base directory.
Workarounds
Validate input before using user-supplied file paths.
References
https://nvd.nist.gov/vuln/detail/CVE-2017-5223
For more information
If you have any questions or comments about this advisory:
- Open a private issue in the PHPMailer project
Impact
Arbitrary local files can be attached to email messages.
CVE-2017-5223 has a CVSS score of 5.5 (Medium). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (5.2.22); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Fixed in 5.2.22
Frequently Asked Questions
- What is CVE-2017-5223? CVE-2017-5223 is a medium-severity security vulnerability in phpmailer/phpmailer (composer), affecting versions >= 5.0.0, < 5.2.22. It is fixed in 5.2.22.
- How severe is CVE-2017-5223? CVE-2017-5223 has a CVSS score of 5.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of phpmailer/phpmailer are affected by CVE-2017-5223? phpmailer/phpmailer (composer) versions >= 5.0.0, < 5.2.22 is affected.
- Is there a fix for CVE-2017-5223? Yes. CVE-2017-5223 is fixed in 5.2.22. Upgrade to this version or later.
- Is CVE-2017-5223 exploitable, and should I be worried? Whether CVE-2017-5223 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2017-5223 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2017-5223? Upgrade
phpmailer/phpmailerto 5.2.22 or later.