Comodo Internet Security's firewall driver Inspect.sys contains an integer underflow in its IPv6 packet parser. The parser decrements an unsigned 64-bit payload-length value (taken from the IPv6 fixed header's payload length field) by the size of each IPv6 extension header without validating it, so a packet whose declared payload length is smaller than the sum of its extension-header lengths underflows the value to a near-maximal 64-bit integer. Because IPv6 parsing occurs before firewall rule enforcement, a remote, unauthenticated attacker can send a single crafted IPv6 packet - even to a host with all ports blocked - to trigger an out-of-bounds read (and, on a separate code path, an oversized memcpy) in the Windows kernel at DISPATCH_LEVEL, crashing the system (BSOD).

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Comodo Comodo Internet Security unaffected
Version Status Constraints
0 affected ≤ 12.3.4.8162

No data.

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Project Subscriptions

Vendors Products
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Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/MalwareTech/ComoDoS cve-icon cve-icon
https://malwaretech.com/2026/06/exploiting-a-remote-kernel-vulnerability-in-comodo-internet-security.html cve-icon cve-icon
https://www.vulncheck.com/advisories/comodo-internet-security-inspect-sys-ipv6-integer-underflow-remote-denial-of-service cve-icon cve-icon
History

Sun, 07 Jun 2026 12:30:00 +0000

Type Values Removed Values Added
Description Comodo Internet Security's firewall driver Inspect.sys contains an integer underflow in its IPv6 packet parser. The parser decrements an unsigned 64-bit payload-length value (taken from the IPv6 fixed header's payload length field) by the size of each IPv6 extension header without validating it, so a packet whose declared payload length is smaller than the sum of its extension-header lengths underflows the value to a near-maximal 64-bit integer. Because IPv6 parsing occurs before firewall rule enforcement, a remote, unauthenticated attacker can send a single crafted IPv6 packet - even to a host with all ports blocked - to trigger an out-of-bounds read (and, on a separate code path, an oversized memcpy) in the Windows kernel at DISPATCH_LEVEL, crashing the system (BSOD).
Title Comodo Internet Security Inspect.sys IPv6 Integer Underflow Remote Denial of Service
First Time appeared Comodo
Comodo internet Security
Weaknesses CWE-191
CPEs cpe:2.3:a:comodo:internet_security:*:*:*:*:*:*:*:*
Vendors & Products Comodo
Comodo internet Security
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.7, 'vector': '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'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-06-07T12:08:59.492Z

Reserved: 2026-05-31T11:54:34.993Z

Link: CVE-2026-49494

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-06-07T13:16:20.927

Modified: 2026-06-07T13:16:20.927

Link: CVE-2026-49494

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses