Out-of-bounds write in Cpanel::JSON::XS canonical hash encoding
Key facts
- Attack vector
- Network
- Privileges required
- None
- 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-787 and the CVSS impact.
Summary
Cpanel::JSON::XS versions from 4.20 before 4.80 for Perl write out of bounds when a tied or threads::shared hash grows during canonical encoding. The encoder counts the hash keys in one pass and collects them in a second, so keys added between the passes overflow the fixed stack or heap array in encode_hv (CWE-787). A network attacker without privileges or user interaction can corrupt stack or heap memory and crash the process.
Written with Claude Haiku 5.5 from the sources below · 2026-10-30
Description from the CNA
Cpanel::JSON::XS versions from 4.20 before 4.80 for Perl write out of bounds when a tied or shared hash grows during canonical encoding in encode_hv. With canonical, the keys of a tied or threads::shared hash are counted before a second pass collects them for sorting. The encoder uses a fixed 64-entry stack array or, for larger counts, a heap array sized from the first pass. If the second pass exceeds that capacity, entries are written out of bounds before the counts are compared. This corrupts stack or heap memory and can crash the process.
Why it matters now
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
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | Cpanel-JSON-XS | 4.20 to before 4.80 | 4.80 | Patch available | CNA |
- Cpanel-JSON-XS Vendor— Affected 4.20 to before 4.80 Fixed in 4.80 Patch available CNA
Remediation
Upgrade Cpanel-JSON-XS to version 4.80 or later, which fixes the flaw.
Written with Claude Haiku 5.5 from the sources below · 2026-10-30
- Fix · CNA Cpanel-JSON-XS Fixed in 4.80
Vendor assessments
Timeline
- 2026-10-20 Threatist record created from CVE-2026-110680
- 2026-10-20 Alias added: GHSA-7pvv-fpf6-6qmg
- 2026-10-20 Affected versions changed · Red Hat
- 2026-10-20 CVSS score added · Red Hat
- 2026-10-21 CVSS score changed · Red Hat
- 2026-10-30 CVSS score added · CISA ADP
- 2026-10-30 CISA SSVC decision points changed
References
Sources
- CVE-2026-110680 · CVE Program
- CVE-2026-110680 · NVD
- FIRST EPSS
- GHSA-7pvv-fpf6-6qmg · GitHub Advisory Database · CC BY 4.0
- CVE-2026-110680 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences