Byte-string keys misordered in Cpanel::JSON::XS canonical encoding
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA.
Summary
Cpanel::JSON::XS versions from 4.43 before 4.80 for Perl misorder byte-string keys during canonical encoding. Canonical encoding sorts keys by UTF-16 code units, but when a hash has any UTF-8 flagged key, byte-string keys are decoded as UTF-8 for comparison, so they sort out of order (CWE-176). The same data can encode to different canonical documents across processes. A network attacker without privileges or user interaction can trigger it.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
Description from the CNA
Cpanel::JSON::XS versions from 4.43 before 4.80 for Perl misorder byte-string keys during canonical encoding in utf16_cmp. canonical sorts keys by UTF-16 code units. When any key in a hash is UTF-8 flagged, every key is decoded as UTF-8 for the comparison, including byte-string keys that the encoder writes out as Latin-1 characters. A byte-string key whose bytes are valid UTF-8 is sorted out of order, and two keys that encode differently can compare equal and are left in hash order. The same data can encode to different canonical documents across processes.
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 | 4.43 to before 4.80 | 4.80 | Patch available | CNA |
- Cpanel-JSON-XS Vendor— Affected 4.43 to 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
Timeline
- 2026-10-20 Threatist record created from CVE-2026-110687
- 2026-10-20 Alias added: GHSA-fq4p-2pcg-jg87
- 2026-10-20 Affected versions changed · Red Hat
- 2026-10-20 CVSS score added · Red Hat
- 2026-10-21 CVSS score changed · Red Hat
- 2026-10-29 CVSS score added · CISA ADP
- 2026-10-29 CISA SSVC decision points changed
References
Sources
- CVE-2026-110687 · CVE Program
- CVE-2026-110687 · NVD
- FIRST EPSS
- GHSA-fq4p-2pcg-jg87 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-110687 · 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