Xcitium Client Security / Comodo Internet Security Remote Denial of Service
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-191 and the CVSS impact.
Summary
Xcitium Client Security (XCS) before 13.8.2.10019 and Comodo Internet Security (CIS) through 12.3.4.8162 (fix expected by 2026 Q3) contain an integer underflow vulnerability in the firewall driver Inspect.sys that allows remote unauthenticated attackers to crash the system by sending a crafted IPv6 packet with a declared payload length smaller than the sum of its extension-header lengths. The unsigned 64-bit payload-length value underflows to a near-maximal integer, triggering an out-of-bounds read and oversized memcpy in the Windows kernel at DISPATCH_LEVEL, resulting in a blue screen of death even on hosts with all ports blocked.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- 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 |
|---|---|---|---|---|---|
| Xcitium (formerly Comodo Security Solutions) | Comodo Internet Security | up to 12.3.4.8162 | — | No fix listed | CNA |
| Xcitium | Xcitium Client Security (XCS) | before 13.8.2.10019 | 13.8.2.10019 | Patch available | CNA |
- Comodo Internet Security VendorXcitium (formerly Comodo Security Solutions) Affected up to 12.3.4.8162 Fixed in — No fix listed CNA
- Xcitium Client Security (XCS) VendorXcitium Affected before 13.8.2.10019 Fixed in 13.8.2.10019 Patch available CNA
Remediation
- Fix · CNA Xcitium Client Security (XCS) (Xcitium) Fixed in 13.8.2.10019
Timeline
- 2026-10-02 Threatist record created from CVE-2026-49494
- 2026-10-03 Alias added: GHSA-87cf-mxjw-fmjh
- 2026-10-25 EPSS moved to the below the 50th percentile
References
Patch 1
Sources
- CVE-2026-49494 · CVE Program
- CVE-2026-49494 · NVD
- FIRST EPSS
- GHSA-87cf-mxjw-fmjh · GitHub Advisory Database · CC BY 4.0
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