Buffer overflow in PHP

CVE-2025-14178

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.

Vulnerability class: Integer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H.

EPSS exploit prediction

EPSS: 0.005 (37.3th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 37.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-14178: held from 0.005 to 0.005.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: -0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2025-14178?
CVE-2025-14178 is a medium-severity vulnerability in PHP, classified under Integer Overflow or Wraparound. CVSS score: 6.5/10. Published 2025-12-27.
How severe is CVE-2025-14178?
Medium severity. CVSS v3 base score is 6.5 out of 10.