Insufficient output escaping of attachment names in PHPMailer

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS

• CVE-2020-13625: 3.78% estimated exploitation activity in the next 30 days; percentile 89.96 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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…

Published by the source

27 May 2020, 16:37 UTC

Last modified by the source

20 Jan 2023, 22:02 UTC

Source last checked

26 Oct 2026, 13:56 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-f7hx-fqxw-rvvj

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# Patch Next advisory brief: CVE-2020-13625

Advisory: Insufficient output escaping of attachment names in PHPMailer
IDs: CVE-2020-13625, GHSA-f7hx-fqxw-rvvj
Record: https://patchnext.com/advisories/cve-2020-13625 (revision 1, source checked 26 Oct 2026, 13:56 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: phpmailer/phpmailer 6.1.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist phpmailer/phpmailer: affected < 6.1.6; fixed in 6.1.6

## Suggested inspection (read-only)
- Packagist phpmailer/phpmailer: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on phpmailer/phpmailer.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-f7hx-fqxw-rvvj (GitHub-reviewed advisory GHSA-f7hx-fqxw-rvvj lists affected ranges: Packagist phpmailer/phpmailer >=0 <6.1.6)

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