Cross-site scripting in PHPMailer

Description

PHPMailer versions prior to 5.2.24 (released July 26th 2017) have an XSS vulnerability in one of the code examples, CVE-2017-11503. The code_generator.phps example did not filter user input prior to output. This file is distributed with a .phps extension, so it it not normally executable unless it is explicitly renamed, and the file is not included when PHPMailer is loaded through composer, so it is safe by default. There was also an undisclosed potential XSS vulnerability in the default exception handler (unused by default). Patches for both issues kindly provided by Patrick Monnerat of the Fedora Project.

Impact

PHPMailer 5.2.23 has XSS in the "From Email Address" and "To Email Address" fields of code_generator.php.

Patches

Fixed in 5.2.24

Workarounds

None.

References

https://nvd.nist.gov/vuln/detail/CVE-2017-11503

For more information

If you have any questions or comments about this advisory:
* Open a private issue in the PHPMailer project

Basic information

Type
reviewed
Severity
medium
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Not specified
Published (advisory)
2020-03-05 22:09:13 UTC
Updated
2023-01-09 05:02:21 UTC
GitHub reviewed
2020-03-05 22:06:39 UTC

EPSS Score

Score Percentile
2.23% 84.50%

CVSS Scores

Base score Version Severity Vector
6.1 3.0
CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

CWEs

CWE id Name
CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
composer phpmailer/phpmailer >= 5.0.0, < 5.2.24 5.2.24

References

cvelogic Threat Intelligence