CVE-2026-49494
Xcitium Client Security / Comodo Internet Security Remote Denial of Service
- State
- Published
- Severity
- 8.7 High
- Published
- Jun 7, 2026
- Updated
- Jun 23, 2026
- Reserved
- May 31, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.7 High | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N | VulnCheck |
| 3.1 | 7.5 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | VulnCheck |
Weaknesses
- CWE-191 Integer Underflow (Wrap or Wraparound)
Affected Products
| Product | Versions |
|---|---|
Comodo Internet SecurityXcitium (formerly Comodo Security Solutions) |
|
Xcitium Client Security (XCS)Xcitium |
|
References
- MalwareTech - ComoDoStechnical-descriptionexploit
- Proof of Conceptexploit
- Xcitium Release Notesrelease-notespatch
- VulnCheck Advisory: Comodo Internet Security Inspect.sys IPv6 Integer Underflow Remote Denial of Servicethird-party-advisory
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