CVE-2026-49494

HIGH

Comodo Internet Security Inspect.sys IPv6 Integer Underflow Remote Denial of Service

Title source: cna
STIX 2.1

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.

References (5)

Core 5
Core References
Third Party Advisory third-party-advisory
VulnCheck Advisory: Comodo Internet Security Inspect.sys IPv6 Integer Underflow Remote Denial of Service
https://www.vulncheck.com/advisories/comodo-internet-security-inspect-sys-ipv6-integer-underflow-remote-denial-of-service
Patch release-notes patch
Xcitium Release Notes
https://updates.xcitium.com/#note11312
Third Party Advisory third-party-advisory
VulnCheck Advisory: Comodo Internet Security Inspect.sys IPv6 Integer Underflow Remote Denial of Service
https://www.vulncheck.com/advisories/xcitium-client-security-comodo-internet-security-remote-dos

Scores

CVSS v3 7.5
EPSS 0.0054
EPSS Percentile 42.4%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation poc
Automatable yes
Technical Impact partial

Details

CWE
CWE-191
Status published
Products (3)
Comodo/Comodo Internet Security < 12.3.4.8162
Xcitium/Xcitium Client Security (XCS) < 13.8.2.10019
Xcitium (formerly Comodo Security Solutions)/Comodo Internet Security < 12.3.4.8162
Published Jun 07, 2026
Tracked Since Jun 07, 2026