Integer overflow in Comodo Internet Security
CVE-2026-49494
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.008 (54.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 54.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.008 · change: +0.003
Affected products
- Comodo Internet Security — versions 0
- Xcitium Client Security (Xcs) — versions 0
- Xcitium (Formerly Comodo Security Solutions) Internet — versions 0
Weakness classification (CWE)
References
- github.com/MalwareTech/ComoDoS (exploit)
- malwaretech.com/2026/06/exploiting-a-remote-kernel-vulnerability-in-comodo-inte… (technical-description, exploit)
- www.vulncheck.com/advisories/comodo-internet-security-inspect-sys-ipv6-integer-… (third-party-advisory)
- updates.xcitium.com/ (release-notes, patch)
- www.vulncheck.com/advisories/xcitium-client-security-comodo-internet-security-r… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-49494?
- CVE-2026-49494 is a high-severity vulnerability in Comodo Internet Security, classified under Integer Underflow. CVSS score: 7.5/10. Published 2026-06-07.
- How severe is CVE-2026-49494?
- High severity. CVSS v3 base score is 7.5 out of 10.