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CVE-2026-76491— Cisco Expressway Series Software Hardening Release: October 2026 - Denial of Service Vulnerabilities

Quick assessment

Affected
Cisco Cisco TelePresence Video Communication Server (VCS) Expressway
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

作为思科持续致力于主动安全和产品品质的一部分，Cisco Expressway 系列软件工程团队开展了一次全面的内部安全审查。此次审查促使发布了软件加固版本，以修复多个内部发现的安全漏洞。 由 CVE-2026-76491 跟踪的漏洞涉及“可达断言”问题，这些问题归类于通用弱点枚举（CWE）中的基础 CWE-617。

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 94

VendorProduct Version RangeStatus
Cisco Cisco TelePresence Video Communication Server (VCS) Expressway X8.11.2 affected
X8.6 affected
X8.11.3 affected
X8.2.2 affected
X8.8.3 affected
X8.11.0 affected
X12.5.2 affected
X8.1.1 affected
… +86 more rows
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I. Basic Information for CVE-2026-76491

Vulnerability Information
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Vulnerability Title
Cisco Expressway Series Software Hardening Release: October 2026 - Denial of Service Vulnerabilities
Source: CVE Program / CVE List V5
Vulnerability Description
As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco Expressway Series software engineering team has conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities.   The vulnerabilities tracked by CVE-2026-76491 are related to issues concerning reachable assertions that are grouped under the Common Weakness Enumeration (CWE) Base CWE-617.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
可达断言
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Cisco Cisco TelePresence Video Communication Server (VCS) Expressway X8.11.2 -

II. Public POCs for CVE-2026-76491

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III. Intelligence Information for CVE-2026-76491

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Other References for CVE-2026-76491 (1)

Same Patch Batch · Cisco · 2026-10-21 · 34 CVEs total

CVE-2026-76466 9.8 CRITICAL Cisco Expressway Series Remote Code Execution Vulnerability
CVE-2026-76473 9.8 CRITICAL Cisco Unified Communications Products Hardening Release: October 2026 - Improper control o
CVE-2026-76474 9.8 CRITICAL Cisco Unified Communications Products Hardening Release: October 2026 - Improper Authentic
CVE-2026-76475 9.3 CRITICAL Cisco Unified Communications Products Hardening Release: October 2026 - Cross-site Scripti
CVE-2026-20043 9.0 CRITICAL Multiple Cisco Products Snort 3 Software Hardening Release: October 2026
CVE-2026-76477 8.8 HIGH Cisco Unified Communications Products Hardening Release: October 2026 - Injection Vulnerab
CVE-2026-76476 8.8 HIGH Cisco Unified Communications Products Hardening Release: October 2026 - Improper Input Val
CVE-2026-76478 8.8 HIGH Cisco Unified Communications Products Hardening Release: October 2026 - Improper Access Co
CVE-2026-76490 8.6 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - Out-of-bounds Write Vul
CVE-2026-76524 7.8 HIGH Open Source Snort 3 Control Channel Socket Aribitrary Command Execution Vulnerability
CVE-2026-20291 7.8 HIGH Multiple Cisco Products Snort 3 Software Hardening Release: October 2026
CVE-2026-76479 7.8 HIGH Cisco Unified Communications Products Hardening Release: October 2026 - Path Traversal Vul
CVE-2026-76494 7.8 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - Code Injection Vulnerab
CVE-2026-76495 7.8 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - Incorrect Permission As
CVE-2026-76481 7.5 HIGH Cisco Unified Communications Products Hardening Release: October 2026 - Improper Check or
CVE-2026-76492 7.5 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - NULL Pointer Vulnerabil
CVE-2026-76493 7.5 HIGH Cisco Expressway Series Software Hardening Release: October 2026 - Uncaught Exception Vuln
CVE-2026-20356 7.5 HIGH Multiple Cisco Products Snort 3 Software Hardening Release: October 2026
CVE-2026-20236 7.5 HIGH Multiple Cisco Products Snort 3 Software Hardening Release: October 2026
CVE-2026-76505 7.5 HIGH Cisco IOS XR Software for ASR 9000 Series Routers IPv4 Unicast Packets Denial of Service V

Showing top 20 of 34 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Cisco TelePresence Video Communication Server (VCS) Expressway
Same vendor: Cisco
Same weakness: CWE-617

V. Comments for CVE-2026-76491

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