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Fencer Intel
medium 5.6

CVE-2025-40929 json

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

published last yr. modified 4mo ago also EUVD-2025-27140

cvss
5.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 41%
public exploits
0
none known

Summary

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

Patch / fix

  • RURBAN Cpanel::JSON::XS 4.40
  • libcpanel-json-xs-perl Debian 12 4.35-1+deb12u1
  • libcpanel-json-xs-perl Debian 13 4.39-2~deb13u1
  • libcpanel-json-xs-perl Debian 14 4.39-2

debian advisories DEBIAN-CVE-2025-40929

  • libcpanel-json-xs-perl Ubuntu 22.04 LTS 4.27-1ubuntu0.2
  • libcpanel-json-xs-perl Ubuntu 24.04 LTS 4.37-1ubuntu0.1
  • libcpanel-json-xs-perl Ubuntu 26.04 LTS, Ubuntu 25.10 4.39-2

ubuntu advisories UBUNTU-CVE-2025-40929

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • perl-Cpanel-JSON-XS SLE Module for Package Hub 15 SP7 4.800.0-150700.3.9.1
  • perl-Cpanel-JSON-XS SLE Module for Package Hub 15 SP7 4.380.0-150700.3.3.1

suse advisories SUSE-SU-2026:4926-1SUSE-SU-2025:03193-1

  • perl-Cpanel-JSON-XS openSUSE Leap 16.0 4.420.0-bp160.1.1
  • perl-Cpanel-JSON-XS openSUSE Tumbleweed 4.400.0-1.1

opensuse advisories openSUSE-SU-2026:21140-1openSUSE-SU-2025:15534-1

  • perl-cpanel-json-xs Alpine 3.24, Alpine 3.23, Alpine 3.22 +2 more 4.40-r0

alpine advisories ALPINE-CVE-2025-40929

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Is CVE-2025-40929 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-40929 updated cvss 7.5

Cpanel-JSON-XS: integer buffer overflow causing a segfault when parsing crafted JSON

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

0.48% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.6 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
CNA 3.1 5.6 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

Classification

Weakness
  • CWE-122 Heap-based Buffer Overflow

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.