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.
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Affected Vendors & Products
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Solution
Upgrade to Cpanel-JSON-XS 4.80 or later.
Workaround
No workaround given by the vendor.
Mon, 19 Oct 2026 18:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | Cpanel::JSON::XS versions before 4.80 for Perl allow memory exhaustion by encoding exponent notation as full decimal digits under allow_bignum | |
| Weaknesses | CWE-405 | |
| References |
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Projects
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MITRE
Status: PUBLISHED
Assigner: CPANSec
Published:
Updated: 2026-10-19T18:11:45.805Z
Reserved: 2026-10-14T13:23:56.248Z
Link: CVE-2026-110676
Vulnrichment
No data.
NVD
Status : Awaiting Analysis
Published: 2026-10-19T19:17:21.320
Modified: 2026-10-19T20:50:17.967
Link: CVE-2026-110676
Redhat
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OpenCVE Enrichment
Updated: 2026-10-19T19:30:02Z