CVE-2025-14178: Heap buffer overflow in array_merge()

Severity: high (CVSS 8.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-12-27 · updated 2026-10-13
Weakness: CWE-190

Description

In PHP versions:8.1.* before 8.1.34, 8.2.* before 8.2.30, 8.3.* before 8.3.29, 8.4.* before 8.4.16, 8.5.* before 8.5.1, a heap buffer overflow occurs in array_merge() when the total element count of packed arrays exceeds 32-bit limits or HT_MAX_SIZE, due to an integer overflow in the precomputation of element counts using zend_hash_num_elements(). This may lead to memory corruption or crashes and affect the integrity and availability of the target server.

Affected products

PHP: from 8.1.0 before 8.1.34; from 8.2.0 before 8.2.30; from 8.3.0 before 8.3.29; from 8.4.0 before 8.4.16; from 8.5.0 before 8.5.1 — fixed in 8.1.34, 8.2.30, 8.3.29, 8.4.16, 8.5.1

How to fix

Upgrade to a fixed version: PHP 8.1.34, 8.2.30, 8.3.29, 8.4.16. Check the vendor advisory for mitigations.

References

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