Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2021-3603

25
FAUCET Score

CVE-2021-3603 affects PHPMailer versions 6.4.1 and earlier, allowing untrusted code execution if a function named 'php' exists in the global namespace and the validateAddress() function's $patternselect parameter is set to its default 'php' value. This vulnerability carries a high severity CVSS score of 8.1, indicating a network-based attack with high impact on confidentiality, integrity, and availability, though with high attack complexity. There is currently no evidence of active exploitation, and no public exploit code (Metasploit, Nuclei, ExploitDB) is available. Community discussion and media coverage are minimal, suggesting low public awareness.

Impacted Technologies

VendorProductVersion(s)CPE
<= 6.4.1CPE matchmatch criteria
cpe:2.3:a:phpmailer_project:phpmailer:*:*:*:*:*:*:*:*
33CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
34CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
< 6.5.0CPE match
cpe:2.3:a:phpmailer:phpmailer:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.1HIGH

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.2
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
2.26%
Probability of exploitation in next 30 days
EPSS Percentile
81.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.0226 is in the 38th percentile among its peer group of 8,914 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

composerpatch availablevia ghsa
Product: phpmailer/phpmailerFixed in: 6.5.0
github_advisorypatch availablevia nvd_reference
View patch

Vendor Advisories (1)

composerGHSA-77mr-wc79-m8j3high

PHPMailer untrusted code may be run from an overridden address validator

Jun 22, 2021

References

github.com / PHPMailer/PHPMailer/commit/45f3c18dc6a2de1cb1bf49b9b249a9ee36a5f7f3
PatchThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/3YRMWGA4VTMXFB22KICMB7YMFZNFV3EJ
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/FJYSOFCUBS67J3TKR74SD3C454N7VTYM
huntr.dev / bounties/1-PHPMailer/PHPMailer
Product