CPANSA-Cpanel-JSON-XS-2026-110676: Cpanel-JSON-XS vulnerability
| Publisher | giterlizzi | Document category | csaf_security_advisory |
|---|---|---|---|
| Initial release date | 2026-10-19T00:00:00 | Engine | CSAF Perl Toolkit 0.26 |
| Current release date | 2026-10-19T00:00:00 | Build Date | |
| Current version | 1 | Status | final |
| CVSS v3.1 Base Score | 7.5 | Severity | High |
| Original language | Language | en | |
| Also referred to | |||
Vulnerability Description
Cpanel::JSON::XS versions before 4.80 for Perl allow memory exhaustion by encoding exponent notation as full decimal digits under allow_bignum.
With allow_bignum, a JSON number with a fraction or exponent decodes to a Math::BigFloat, which stores the exponent separately and so decodes cheaply. Encoding it untyped or as JSON_TYPE_FLOAT writes the plain decimal form with one digit per unit of exponent. Nothing bounds the exponent, so the 12-byte text [1e30000000] encodes to 30 MB.
Untrusted JSON decoded with allow_bignum and encoded again can exhaust memory and CPU.
Vulnerabilities
CVE-2026-110676
Vulnerability DescriptionCpanel::JSON::XS versions before 4.80 for Perl allow memory exhaustion by encoding exponent notation as full decimal digits under allow_bignum.
With allow_bignum, a JSON number with a fraction or exponent decodes to a Math::BigFloat, which stores the exponent separately and so decodes cheaply. Encoding it untyped or as JSON_TYPE_FLOAT writes the plain decimal form with one digit per unit of exponent. Nothing bounds the exponent, so the 12-byte text [1e30000000] encodes to 30 MB.
Untrusted JSON decoded with allow_bignum and encoded again can exhaust memory and CPU.
| Weakness | CWE-405 : Asymmetric Resource Consumption (Amplification) |
|---|
Product status
Known affected
| Product | Score | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Cpanel-JSON-XS less than 4.80 |
|
Fixed
- Cpanel-JSON-XS greater than or equal 4.80
giterlizzi
Namespace: https://github.com/giterlizzi/
gdt@cpan.org
References
- CPANSA-Cpanel-JSON-XS-2026-110676 JSON self
https://raw.githubusercontent.com/giterlizzi/perl-CPANSA-CSAF/develop/csaf/white/2026/cpansa-cpanel-json-xs-2026-110676.json - https://github.com/rurban/Cpanel-JSON-XS/commit/996ab96972b967a917536d291947b5f3cf42e960.patch external
https://github.com/rurban/Cpanel-JSON-XS/commit/996ab96972b967a917536d291947b5f3cf42e960.patch - https://metacpan.org/release/RURBAN/Cpanel-JSON-XS-4.80/changes external
https://metacpan.org/release/RURBAN/Cpanel-JSON-XS-4.80/changes - CVE-2026-110676 (NVD) external
https://nvd.nist.gov/vuln/detail/CVE-2026-110676
Revision history
| Version | Date of the revision | Summary of the revision |
|---|---|---|
| 1 | Mon Oct 19 00:00:00 2026 | First release |
Sharing rules
TLP:WHITE
For the TLP version see: https://www.first.org/tlp/