CVE-2026-110680
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Cpanel::JSON::XS Perl Module Heap Buffer Overflow in encode_hv

Publication date: 2026-10-19

Last updated on: 2026-10-19

Assigner: CPANSec

Description
Cpanel::JSON::XS versions from 4.20 before 4.80 for Perl write out of bounds when a tied or shared hash grows during canonical encoding in encode_hv. With canonical, the keys of a tied or threads::shared hash are counted before a second pass collects them for sorting. The encoder uses a fixed 64-entry stack array or, for larger counts, a heap array sized from the first pass. If the second pass exceeds that capacity, entries are written out of bounds before the counts are compared. This corrupts stack or heap memory and can crash the process.

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Meta Information

Published
2026-10-19
Last Modified
2026-10-19
Generated
2026-10-21
AI Q&A
2026-10-19
EPSS Evaluated
N/A
NVD
CVE-2026-110680
EUVD
EUVD-2026-104560

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
cpanel json_xs From 4.20 (inc) to 4.80 (exc)
rurban cpanel_json_xs From 4.20 (inc) to 4.80 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-787 The product writes data past the end, or before the beginning, of the intended buffer.

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Executive Summary

This vulnerability affects Cpanel::JSON::XS versions 4.20 to 4.80 for Perl. It occurs during canonical encoding when a tied or shared hash grows between counting keys and collecting them for sorting. The encoder uses a fixed-size array or heap array based on the initial key count. If the hash grows, the second pass writes out of bounds, corrupting memory and potentially crashing the process.

Detection Guidance

This vulnerability can be detected by checking the version of Cpanel::JSON::XS installed on your system. If you are running a version between 4.20 and 4.80, you are vulnerable. Use the command 'cpan Cpanel::JSON::XS' or 'perl -MCpanel::JSON::XS -e "print $Cpanel::JSON::XS::VERSION"

Additionally, monitor for crashes or memory corruption errors in applications using Cpanel::JSON::XS, especially when processing tied or shared hashes. The patch in Resource 1 includes a test case that can be run to verify if the vulnerability is present.

Impact Analysis

This vulnerability can cause crashes or undefined behavior in applications using affected versions of Cpanel::JSON::XS. If an attacker triggers the issue by manipulating tied hashes, it may lead to denial of service or memory corruption in the application process.

Compliance Impact

This vulnerability primarily causes crashes or undefined behavior due to memory corruption when processing tied hashes with unstable key counts. It does not directly impact compliance with standards like GDPR or HIPAA, as those focus on data protection, privacy, and security controls rather than memory safety issues.

Mitigation Strategies

Update Cpanel::JSON::XS to version 4.80 or later to address the out-of-bounds write issue in encode_hv.

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