Stack exhaustion in Cpanel::JSON::XS via nested tagged values
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-674.
Summary
Cpanel::JSON::XS versions before 4.80 for Perl are affected. When allow_tags is enabled, nested tagged values are decoded recursively without being counted against max_depth. An unauthenticated remote attacker can send a long run of "(" bytes that exhausts the C stack (CWE-674), causing an uncatchable segmentation fault and a denial of service.
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 stack exhaustion via nested tagged values under allow_tags in decode_tag. With allow_tags, "(" starts a tagged value. Its tag and value are decoded recursively, and each can start another tagged value. Unlike arrays and objects, this nesting is not counted against max_depth. A run of "(" bytes exhausts the C stack and triggers an uncatchable segmentation fault regardless of max_depth.
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 | before 4.80 | 4.80 | Patch available | CNA |
- Cpanel-JSON-XS Vendor— Affected before 4.80 Fixed in 4.80 Patch available CNA
Remediation
Cpanel-JSON-XS is fixed in version 4.80. Upgrade to 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-2026-110673
- 2026-10-20 Alias added: GHSA-fgcx-mvpm-hff9
- 2026-10-21 Affected versions changed · Red Hat
- 2026-10-21 CVSS score added · Red Hat
- 2026-10-29 CVSS score added · CISA ADP
- 2026-10-29 CISA SSVC decision points changed
References
Sources
- CVE-2026-110673 · CVE Program
- CVE-2026-110673 · NVD
- FIRST EPSS
- GHSA-fgcx-mvpm-hff9 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-110673 · 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