Vulnerability · Published Jun 7, 2026 · Assigned by VulnCheck
CVE-2026-49494Xcitium Client Security / Comodo Internet Security Remote Denial of Service
High 7.5
In plain English
A high-severity security flaw in Xcitium Client Security (XCS) from Xcitium. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 46% of all known vulnerabilities).
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Xcitium (formerly Comodo Security Solutions) | Comodo Internet Security | 0 – through 12.3.4.8162 |
| Xcitium | Xcitium Client Security (XCS) | 0 – before 13.8.2.10019 |
Weakness: CWE-191 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- MalwareTech - ComoDoS technical-description, exploit
- Proof of Concept exploit
- Xcitium Release Notes release-notes, patch
- VulnCheck Advisory: Comodo Internet Security Inspect.sys IPv6 Integer Underflow Remote Denial of Service third-party-advisory