What is CVE-2025-40929?

CVE-2025-40929 is a medium-severity vulnerability in Rurban Cpanel::json::xs, classified under Heap-based Buffer Overflow. CVSS score: 5.6/10. Published 2025-09-08.

How severe is CVE-2025-40929?

Medium severity. CVSS v3 base score is 5.6 out of 10.

Is CVE-2025-40929 known to be exploited?

3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Buffer overflow in Rurban Cpanel::json::xs

CVE-2025-40929

Cpanel::JSON::XS before version 4.40 for Perl has an integer buffer overflow causing a segfault when parsing crafted JSON, enabling denial-of-service attacks or other unspecified impact

Vulnerability class: Buffer Overflow

EPSS: 0.004 (32.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.6 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L.

Affected products

Rurban Cpanel::json::xs — versions 0

Weakness classification (CWE)

CWE-122 — Heap-based Buffer Overflow

Public proof-of-concept exploits

References

9b29abf9-4ab0-4765-b253-1875cd9b441e (related)
9b29abf9-4ab0-4765-b253-1875cd9b441e (release-notes)
9b29abf9-4ab0-4765-b253-1875cd9b441e (patch)
af854a3a-2127-422b-91ae-364da2661108
af854a3a-2127-422b-91ae-364da2661108

Frequently asked questions

What is CVE-2025-40929?: CVE-2025-40929 is a medium-severity vulnerability in Rurban Cpanel::json::xs, classified under Heap-based Buffer Overflow. CVSS score: 5.6/10. Published 2025-09-08.
How severe is CVE-2025-40929?: Medium severity. CVSS v3 base score is 5.6 out of 10.
Is CVE-2025-40929 known to be exploited?: 3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.