What’s Vulnerable › Vulnerabilities

CVE-2026-49494: Xcitium Client Security / Comodo Internet Security Remote Denial of Service

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-07 · updated 2026-07-23
• Weakness: CWE-191

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

• Xcitium Client Security (XCS): before 13.8.2.10019 — fixed in 13.8.2.10019
• Xcitium (formerly Comodo Security Solutions) Comodo Internet Security: through 12.3.4.8162

How to fix

Upgrade to a fixed version: Xcitium Client Security (XCS) 13.8.2.10019. Check the vendor advisory for mitigations.

References

• https://github.com/MalwareTech/ComoDoS
• https://malwaretech.com/2026/06/exploiting-a-remote-kernel-vulnerability-in-comodo-internet-security.html
• https://updates.xcitium.com/#note11312
• https://www.vulncheck.com/advisories/xcitium-client-security-comodo-internet-security-remote-dos

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