CVE-2026-49494: Integer Underflow (Wrap or Wraparound) in Xcitium (formerly Comodo Security Solutions) Comodo Internet Security
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.
AI Analysis
Technical Summary
CVE-2026-49494 is an integer underflow vulnerability in the Inspect.sys firewall driver component of Xcitium Client Security (XCS) and Comodo Internet Security (CIS). The vulnerability arises when a crafted IPv6 packet declares a payload length smaller than the total length of its extension headers. This causes the unsigned 64-bit payload-length value to underflow to a near-maximum integer, triggering an out-of-bounds read and an oversized memcpy operation at DISPATCH_LEVEL in the Windows kernel. The result is a system crash (blue screen of death) even if all ports are blocked. The vulnerability affects XCS versions before 13.8.2.10019 and CIS versions through 12.3.4.8162. No patch or official remediation is currently available, but a fix is expected by Q3 2026.
Potential Impact
Successful exploitation allows remote unauthenticated attackers to cause a denial of service by crashing the affected system via a crafted IPv6 packet. This results in a blue screen of death, disrupting availability. The vulnerability does not require user interaction or privileges and bypasses port blocking, making it highly impactful for system stability.
Mitigation Recommendations
No official patch or remediation is currently available. A fix is expected by Q3 2026. Until then, administrators should monitor vendor advisories for updates. No other vendor-provided mitigations or workarounds are documented at this time.
CVE-2026-49494: Integer Underflow (Wrap or Wraparound) in Xcitium (formerly Comodo Security Solutions) Comodo Internet Security
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.
CVSS v4.0
Score 8.7high
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-49494 is an integer underflow vulnerability in the Inspect.sys firewall driver component of Xcitium Client Security (XCS) and Comodo Internet Security (CIS). The vulnerability arises when a crafted IPv6 packet declares a payload length smaller than the total length of its extension headers. This causes the unsigned 64-bit payload-length value to underflow to a near-maximum integer, triggering an out-of-bounds read and an oversized memcpy operation at DISPATCH_LEVEL in the Windows kernel. The result is a system crash (blue screen of death) even if all ports are blocked. The vulnerability affects XCS versions before 13.8.2.10019 and CIS versions through 12.3.4.8162. No patch or official remediation is currently available, but a fix is expected by Q3 2026.
Potential Impact
Successful exploitation allows remote unauthenticated attackers to cause a denial of service by crashing the affected system via a crafted IPv6 packet. This results in a blue screen of death, disrupting availability. The vulnerability does not require user interaction or privileges and bypasses port blocking, making it highly impactful for system stability.
Mitigation Recommendations
No official patch or remediation is currently available. A fix is expected by Q3 2026. Until then, administrators should monitor vendor advisories for updates. No other vendor-provided mitigations or workarounds are documented at this time.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-05-31T11:54:34.993Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a25619ce29bf47b50cbf0bd
Added to database: 06/07/2026, 12:18:36 UTC
Last enriched: 06/23/2026, 15:51:16 UTC
Last updated: 07/24/2026, 08:52:04 UTC
Views: 159
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