CVE-2021-3603: Phpmailer/phpmailer PHPMailer Untrusted Code May Be Vulnerability
HIGHCVE-2021-3603 is a HIGH (CVSS 8.1) phpmailer untrusted code may be vulnerability (CWE-829: Inclusion of Functionality from Untrusted Control Sphere) affecting Phpmailer/phpmailer libraries in the Packagist ecosystem. The issue involves phpmailer untrusted code may be run from an overridden address validator. Remediation is available by upgrading affected packages to version 6.5.0.
CVE-2021-3603 at a Glance
Security Impact
CVSS: 8.1
The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H).
How to Fix CVE-2021-3603
To remediate this vulnerability, upgrade all affected Phpmailer/phpmailer dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.
Upgrade phpmailer/phpmailer to 6.5.0Run the following command in your project directory to verify that all resolved dependencies use the patched release:
inspect dependencies for phpmailer/phpmailerHow to Check if You Are Affected
To determine whether your application is affected by CVE-2021-3603, inspect your project dependencies for Phpmailer/phpmailer:
inspect dependencies for phpmailer/phpmailerAnalyze the terminal output to locate any version of Phpmailer/phpmailer in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 6.5.0), your application is affected.
Note: Verify declared build manifests and deployed runtime container environments.
Technical Details
Vulnerability Mechanism & Technical Analysis
This vulnerability is classified under CWE-829: Inclusion of Functionality from Untrusted Control Sphere, where the product imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere. In Phpmailer/phpmailer, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.
Source Advisory Statement
CVE-2021-3603 Affected Phpmailer/phpmailer Versions
1 component(s)| Product / Package | Ecosystem | Affected Versions | Fixed Version |
|---|---|---|---|
|
phpmailer/phpmailer
|
Packagist |
< 6.5.0
|
6.5.0
|
References
Frequently Asked Questions
What is CVE-2021-3603?
Which Phpmailer/phpmailer versions are affected?
What version fixes CVE-2021-3603?
Is phpmailer/phpmailer affected?
What is the CVSS score of CVE-2021-3603?
What CWE is associated with CVE-2021-3603?
How can I check Packagist dependencies for CVE-2021-3603?
Machine-readable OSV JSON
OSV v1.5 Schema
{
"schema_version" : "1.4.0",
"id" : "GHSA-77mr-wc79-m8j3",
"modified" : "2024-02-07T18:16:24Z",
"published" : "2021-06-22T15:18:02Z",
"aliases" : [ "CVE-2021-3603" ],
"summary" : "PHPMailer untrusted code may be run from an overridden address validator",
"details" : "If a function is defined that has the same name as the default built-in email address validation scheme (`php`), it will be called in default configuration as when no validation scheme is provided, the default scheme's callable `php` was being called. If an attacker is able to inject such a function into the application (a much bigger issue), it will be called whenever an email address is validated, such as when calling `validateAddress()`.\n\n### Impact\nLow impact – exploitation requires that an attacker can already inject code into an application, but it provides a trigger pathway.\n\n### Patches\nThis is patched in PHPMailer 6.5.0 by denying the use of simple strings as validator function names, which is a very minor BC break.\n\n### Workarounds\nInject your own email validator function.\n\n### References\nReported by [Vikrant Singh Chauhan](mailto:vi@hackberry.xyz) via [huntr.dev](https://www.huntr.dev/).\n[CVE-2021-3603](https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-3603)\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in [the PHPMailer project](https://github.com/PHPMailer/PHPMailer)\n* [Email us](mailto:phpmailer@synchromedia.co.uk).\n",
"severity" : [ {
"type" : "CVSS_V3",
"score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"
} ],
"affected" : [ {
"package" : {
"ecosystem" : "Packagist",
"name" : "phpmailer/phpmailer"
},
"ranges" : [ {
"type" : "ECOSYSTEM",
"events" : [ {
"introduced" : "0"
}, {
"fixed" : "6.5.0"
} ]
} ]
} ],
"references" : [ {
"type" : "WEB",
"url" : "https://github.com/PHPMailer/PHPMailer/security/advisories/GHSA-77mr-wc79-m8j3"
}, {
"type" : "ADVISORY",
"url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-3603"
}, {
"type" : "WEB",
"url" : "https://github.com/PHPMailer/PHPMailer/commit/45f3c18dc6a2de1cb1bf49b9b249a9ee36a5f7f3"
}, {
"type" : "WEB",
"url" : "https://github.com/FriendsOfPHP/security-advisories/blob/master/phpmailer/phpmailer/CVE-2021-3603.yaml"
}, {
"type" : "PACKAGE",
"url" : "https://github.com/PHPMailer/PHPMailer"
}, {
"type" : "WEB",
"url" : "https://github.com/PHPMailer/PHPMailer/releases/tag/v6.5.0"
}, {
"type" : "WEB",
"url" : "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3YRMWGA4VTMXFB22KICMB7YMFZNFV3EJ"
}, {
"type" : "WEB",
"url" : "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FJYSOFCUBS67J3TKR74SD3C454N7VTYM"
}, {
"type" : "WEB",
"url" : "https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-3603"
}, {
"type" : "WEB",
"url" : "https://www.huntr.dev/bounties/1-PHPMailer/PHPMailer"
} ],
"database_specific" : {
"cwe_ids" : [ "CWE-74", "CWE-829" ],
"severity" : "HIGH",
"github_reviewed" : true,
"github_reviewed_at" : "2021-06-16T19:49:12Z",
"nvd_published_at" : "2021-06-17T12:15:00Z"
}
}