CVE-2024-2408: PHP is vulnerable to the Marvin Attack

Severity: medium (CVSS 5.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2024-06-09 · updated 2026-06-17
Weakness: CWE-203

Description

The openssl_private_decrypt function in PHP, when using PKCS1 padding (OPENSSL_PKCS1_PADDING, which is the default), is vulnerable to the Marvin Attack unless it is used with an OpenSSL version that includes the changes from this pull request: https://github.com/openssl/openssl/pull/13817 (rsa_pkcs1_implicit_rejection). These changes are part of OpenSSL 3.2 and have also been backported to stable versions of various Linux distributions, as well as to the PHP builds provided for Windows since the previous release. All distributors and builders should ensure that this version is used to prevent PHP from being vulnerable. PHP Windows builds for the versions 8.1.29, 8.2.20 and 8.3.8 and above include OpenSSL patches that fix the vulnerability.

Affected products

Fedoraproject Fedora: 40
PHP: from 8.1.0 before 8.1.29; from 8.2.0 before 8.2.20; from 8.3.0 before 8.3.8 — fixed in 8.1.29, 8.2.20, 8.3.8

How to fix

Upgrade to a fixed version: PHP 8.1.29, 8.2.20, 8.3.8. Check the vendor advisory for mitigations.

References

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