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TI-2026-76557 Aliases CVE-2026-110676GHSA-qgf5-7gf3-jg2g

Cpanel::JSON::XS memory exhaustion when encoding exponents under allow_bignum

Priority LOW 39CWE-405Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA.

Summary

Cpanel::JSON::XS versions before 4.80 for Perl allow memory exhaustion when encoding decoded numbers. With allow_bignum, a JSON number with an exponent decodes to a Math::BigFloat that stores the exponent cheaply, but encoding it untyped or as JSON_TYPE_FLOAT writes the full decimal form with one digit per unit of exponent, so the 12-byte text [1e30000000] encodes to 30 MB (CWE-405). An unauthenticated remote attacker can exhaust memory and CPU by supplying untrusted JSON that is decoded with allow_bignum and encoded again.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00486 42nd percentileScored 2026-11-07
Fix Fixed Cpanel-JSON-XS: 4.80

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
—Cpanel-JSON-XSbefore 4.804.80Patch availableCNA
  • Cpanel-JSON-XS Vendor— Affected before 4.80 Fixed in 4.80 Patch available CNA

Remediation

Upgrade Cpanel-JSON-XS to version 4.80 or later.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

  • Fix · CNA Cpanel-JSON-XS Fixed in 4.80

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-20 Threatist record created from CVE-2026-110676
  2. 2026-10-20 Alias added: GHSA-qgf5-7gf3-jg2g
  3. 2026-10-20 Affected versions changed · Red Hat
  4. 2026-10-21 CVSS score added · Red Hat
  5. 2026-10-29 CVSS score added · CISA ADP
  6. 2026-10-29 CISA SSVC decision points changed

References

Patch 1

Other 1

Sources

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