CVE-2026-110676 RURBAN CVE debrief

Who should care

Defenders of Perl systems using Cpanel::JSON::XS should verify exposure and take action to upgrade to version 4.80 or later. This includes operators, platform administrators, vulnerability management teams, and security teams who need to assess the impact of this vulnerability on their systems and take appropriate measures.

Why it matters

CVE-2026-110676 is a vulnerability in Cpanel::JSON::XS versions before 4.80 for Perl, which allows memory exhaustion by encoding exponent notation as full decimal digits under allow_bignum. Defenders of Perl systems using Cpanel::JSON::XS should verify exposure and take action to upgrade to version 4.80 or later.

• Potential memory exhaustion attacks
• CPU exhaustion attacks through untrusted JSON decoding and encoding
• Verification of exposure and upgrade to version 4.80 or later

Technical summary

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.

Defensive priority

Defenders should prioritize verifying exposure of Perl systems using Cpanel::JSON::XS and upgrading to version 4.80 or later.

Recommended defensive actions

• Verify exposure of Perl systems using Cpanel::JSON::XS
• Upgrade to version 4.80 or later
• Monitor for potential memory exhaustion attacks
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability, including the affected version and patch information. The vulnerability allows 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-by

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.