medium CVSS 6.5

CVE-2024-3096·PHP vulnerability

In PHP  version 8.1.* before 8.1.28, 8.2.* before 8.2.18, 8.3.* before 8.3.5, if a password stored with password_hash() starts with a null byte (\x00), testing a blank string as the password via password_verify() will incorrectly return true.

Severity
medium
Software
PHP
Fixed in
8.3.5
Published
2024-04-29

Affected versions

From: 8.3.0

Until: 8.3.5

Fixed in: 8.3.5

How to fix this CVE

Upgrade PHP to version 8.3.5 or later to patch a password verification bypass in the password_hash() and password_verify() functions. This vulnerability allows attackers to bypass authentication by submitting a blank password when a stored hash begins with a null byte. Update immediately if you rely on PHP's built-in password functions for authentication.

sudo dnf update php

Defensia detects this vulnerability

How to check if you are affected

  1. Run `php -v` to check your currently installed PHP version and confirm if it falls within the affected range (8.3.0 to 8.3.5)
  2. Search your codebase for uses of password_verify() to identify which applications depend on this function for authentication
  3. Review application logs for repeated failed login attempts followed by successful logins with blank or empty password fields, which may indicate exploitation
  4. After patching, run `php -v` again and verify the version is 8.3.5 or higher, then restart your PHP-FPM or web server service

FAQ

What is CVE-2024-3096?

This vulnerability is a password verification bypass in PHP where password_verify() incorrectly returns true when testing a blank password against a hash that starts with a null byte (\x00). This can lead to unauthorized authentication bypass in applications using PHP's password functions.

Is CVE-2024-3096 being actively exploited?

No, CVE-2024-3096 is not listed in the CISA Known Exploited Vulnerabilities catalog and no public exploits are currently available, though the vulnerability is real and should be patched.

What versions of PHP are affected by CVE-2024-3096?

PHP 8.3.0 through 8.3.5 are affected. Earlier branches 8.1 and 8.2 have their own affected ranges (before 8.1.28 and 8.2.18 respectively).

How do I check if my server is vulnerable to CVE-2024-3096?

Run `php -v` and check if the version is within 8.3.0-8.3.5 (or the affected ranges for 8.1/8.2 branches). Additionally, check your application code for password_verify() function usage.

Does Defensia detect CVE-2024-3096?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If PHP is installed on a monitored server, CVE-2024-3096 will appear in your dashboard with remediation steps.

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References

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