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Type confusion in Cpanel::JSON::XS for Perl decoding duplicate keys

Priority LOW 29CWE-176Published · Updated

Key facts

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

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA. Impact type from CWE-843 and the CVSS impact.

Summary

Cpanel::JSON::XS for Perl from 4.33 before 4.80 fails to detect repeated non-ASCII bare keys, so a repeated key can replace an earlier value. When decoded with relaxed and dupkeys_as_arrayref, a repeated bare key replaces the array that collects a key's values with a plain value, which is then used as an array (CWE-843). A remote attacker with low privileges who supplies untrusted JSON can crash the process or dereference an address chosen by a JSON number.

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

Description from the CNA

Cpanel::JSON::XS versions from 4.33 before 4.80 for Perl miss duplicate non-ASCII bare keys, allowing type confusion under dupkeys_as_arrayref in decode_hv. With allow_barekey, which relaxed enables, a bare key containing a non-ASCII byte is stored as UTF-8 but looked up as raw bytes, so a repeated key escapes the duplicate-key check and replaces the earlier value. From 4.41, under dupkeys_as_arrayref, a bare repeat replaces the array that collects a key's values with a plain value, and the next quoted repeat pushes onto that value as if it were an array. A JSON integer there is dereferenced as a pointer. Untrusted JSON decoded with relaxed and dupkeys_as_arrayref can crash the process or dereference an address chosen by a JSON number.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00514 44th percentileScored 2026-11-07
Fix Fixed Cpanel-JSON-XS: 4.80

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
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-XS4.33 to before 4.804.80Patch availableCNA
  • Cpanel-JSON-XS Vendor— Affected 4.33 to before 4.80 Fixed in 4.80 Patch available CNA

Remediation

Upgrade Cpanel-JSON-XS to version 4.80, the fixed version for affected versions from 4.33 before 4.80.

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-2026-110674
  2. 2026-10-20 Alias added: GHSA-c92x-ph36-v6p2
  3. 2026-10-20 Affected versions changed · Red Hat
  4. 2026-10-20 CVSS score added · Red Hat
  5. 2026-10-21 CVSS score changed · Red Hat
  6. 2026-10-29 CVSS score added · CISA ADP
  7. 2026-10-29 CISA SSVC decision points changed

References

Sources