GHSA-f7hx-fqxw-rvvj is a high-severity (CVSS 7.5) CWE-116 vulnerability in phpmailer/phpmailer. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether GHSA-f7hx-fqxw-rvvj is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Insufficient output escaping of attachment names in PHPMailer
Real-World Exposure
phpmailer/phpmailerReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Impact
CWE-116: Incorrect output escaping.
An attachment added like this (note the double quote within the attachment name, which is entirely valid):
$mail->addAttachment('/tmp/attachment.tmp', 'filename.html";.jpg');
Will result in a message containing these headers:
Content-Type: application/octet-stream; name="filename.html";.jpg"
Content-Disposition: attachment; filename="filename.html";.jpg"
The attachment will be named filename.html, and the trailing ";.jpg" will be ignored. Mail filters that reject .html attachments but permit .jpg attachments may be fooled by this.
Note that the MIME type itself is obtained automatically from the source filename (in this case attachment.tmp, which maps to a generic application/octet-stream type), and not the name given to the attachment (though these are the same if a separate name is not provided), though it can be set explicitly in other parameters to attachment methods.
Patches
Patched in PHPMailer 6.1.6 by escaping double quotes within the name using a backslash, as per RFC822 section 3.4.1, resulting in correctly escaped headers like this:
Content-Type: application/octet-stream; name="filename.html\";.jpg"
Content-Disposition: attachment; filename="filename.html\";.jpg"
Workarounds
Reject or filter names and filenames containing double quote (") characters before passing them to attachment functions such as addAttachment().
References
CVE-2020-13625. PHPMailer 6.1.6 release
For more information
If you have any questions or comments about this advisory:
- Open an issue in the PHPMailer repo
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | phpmailer/phpmailer | all versions | 6.1.6 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for phpmailer/phpmailer. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update phpmailer/phpmailer to 6.1.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-f7hx-fqxw-rvvj is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-f7hx-fqxw-rvvj is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-f7hx-fqxw-rvvj. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-f7hx-fqxw-rvvj in your dependencies?
O3 detects GHSA-f7hx-fqxw-rvvj across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.