CVE-2026-76490 - Vulnerability Details

- Cisco Expressway Series Software Hardening Release: October 2026 - Out-of-bounds Write Vulnerabilities

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-2026-76490 are related to issues concerning out-of-bounds writes that are grouped under the Common Weakness Enumeration (CWE) Base CWE-787.

Published: 2026-10-21

Score: 8.6 High

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

The vulnerability involves an out‑of‑bounds write in Cisco Expressway Series software, which can lead to memory corruption that may allow a remote attacker to hijack program flow or execute arbitrary code, thereby compromising confidentiality, integrity, and availability. This weakness corresponds to CWE-787.

Affected Systems

The Cisco TelePresence Video Communication Server (VCS) Expressway component is affected. No specific version numbers are listed, so all deployments that run the unpatched October 2026 baseline are potentially impacted.

Risk and Exploitability

The CVSS base score of 8.6 indicates high severity. The EPSS score is not available, so the likelihood of exploitation in the wild cannot be quantified. The vulnerability has not been listed in the CISA KEV catalog, suggesting no confirmed widespread exploitation yet. The Expressway software provides network‑connected services, so the likely attack vector is remote; if the system is exposed to the Internet or unsecured networks, the flaw could be exploited by an adversary to compromise the server.

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

Vendor Product Default status Versions

Cisco

Cisco TelePresence Video Communication Server (VCS) Expressway

unknown

Version	Status	Constraints
`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	—
`X8.9`	affected	—
`X12.5.1`	affected	—
`X12.5.6`	affected	—
`X8.7.3`	affected	—
`X12.6.0`	affected	—
`X8.11.1`	affected	—
`X8.5`	affected	—
`X8.9.1`	affected	—
`X8.10.2`	affected	—
`X8.8.2`	affected	—
`X8.5.3`	affected	—
`X8.1`	affected	—
`X8.9.2`	affected	—
`X8.11.4`	affected	—
`X12.5.4`	affected	—
`X8.8.1`	affected	—
`X8.2.1`	affected	—
`X8.5.1`	affected	—
`X8.6.1`	affected	—
`X8.1.2`	affected	—
`X8.8`	affected	—
`X8.10.0`	affected	—
`X12.5.3`	affected	—
`X8.10.1`	affected	—
`X12.5.7`	affected	—
`X8.10.3`	affected	—
`X8.7.1`	affected	—
`X8.2`	affected	—
`X12.5.8`	affected	—
`X8.7`	affected	—
`X8.5.2`	affected	—
`X12.5.9`	affected	—
`X12.5.0`	affected	—
`X8.10.4`	affected	—
`X8.7.2`	affected	—
`X12.5.5`	affected	—
`X12.6.1`	affected	—
`X12.6.2`	affected	—
`X12.6.3`	affected	—
`X12.6.4`	affected	—
`X12.7.0`	affected	—
`X12.7.1`	affected	—
`X14.0.0`	affected	—
`X14.0.1`	affected	—
`X14.0.2`	affected	—
`X14.0.3`	affected	—
`X14.0.4`	affected	—
`X14.0.5`	affected	—
`X14.0.6`	affected	—
`X14.0.7`	affected	—
`X14.0.8`	affected	—
`X14.2.0`	affected	—
`X14.0.9`	affected	—
`X14.2.1`	affected	—
`X14.2.2`	affected	—
`X14.0.11`	affected	—
`X14.2.5`	affected	—
`X14.0.10`	affected	—
`X14.2.6`	affected	—
`X14.2.7`	affected	—
`X14.3.0`	affected	—
`X14.3.1`	affected	—
`X14.3.2`	affected	—
`X14.3.3`	affected	—
`X15.0.0`	affected	—
`X14.3.4`	affected	—
`X14.3.5`	affected	—
`X15.0.1`	affected	—
`X15.0.2`	affected	—
`X15.0.3`	affected	—
`X14.3.6`	affected	—
`X15.2.0`	affected	—
`X15.2.1`	affected	—
`X15.2.2`	affected	—
`X15.2.3`	affected	—
`X14.3.7`	affected	—
`X15.2.4.`	affected	—
`X15.2.4`	affected	—
`X15.3.0`	affected	—
`X15.3.1`	affected	—
`X15.3.2`	affected	—
`X15.4.0`	affected	—
`X15.5.0`	affected	—
`X15.5.1`	affected	—
`X15.5.2`	affected	—

No data.

Vendor Product Confidence Versions

Cisco

Expressway Series

100%

Version	Status	Scheme	Platform
`[X8.11.2,*]`	affected	generic	—
`[X8.6,*]`	affected	generic	—
`[X8.11.3,*]`	affected	generic	—
`[X8.2.2,*]`	affected	generic	—
`[X8.8.3,*]`	affected	generic	—
`[X8.11.0,*]`	affected	generic	—
`[X12.5.2,*]`	affected	generic	—
`[X8.1.1,*]`	affected	generic	—
`[X8.9,*]`	affected	generic	—
`[X12.5.1,*]`	affected	generic	—
`[X12.5.6,*]`	affected	generic	—
`[X8.7.3,*]`	affected	generic	—
`[X12.6.0,*]`	affected	generic	—
`[X8.11.1,*]`	affected	generic	—
`[X8.5,*]`	affected	generic	—
`[X8.9.1,*]`	affected	generic	—
`[X8.10.2,*]`	affected	generic	—
`[X8.8.2,*]`	affected	generic	—
`[X8.5.3,*]`	affected	generic	—
`[X8.1,*]`	affected	generic	—
`[X8.9.2,*]`	affected	generic	—
`[X8.11.4,*]`	affected	generic	—
`[X12.5.4,*]`	affected	generic	—
`[X8.8.1,*]`	affected	generic	—
`[X8.2.1,*]`	affected	generic	—
`[X8.5.1,*]`	affected	generic	—
`[X8.6.1,*]`	affected	generic	—
`[X8.1.2,*]`	affected	generic	—
`[X8.8,*]`	affected	generic	—
`[X8.10.0,*]`	affected	generic	—
`[X12.5.3,*]`	affected	generic	—
`[X8.10.1,*]`	affected	generic	—
`[X12.5.7,*]`	affected	generic	—
`[X8.10.3,*]`	affected	generic	—
`[X8.7.1,*]`	affected	generic	—
`[X8.2,*]`	affected	generic	—
`[X12.5.8,*]`	affected	generic	—
`[X8.7,*]`	affected	generic	—
`[X8.5.2,*]`	affected	generic	—
`[X12.5.9,*]`	affected	generic	—
`[X12.5.0,*]`	affected	generic	—
`[X8.10.4,*]`	affected	generic	—
`[X8.7.2,*]`	affected	generic	—
`[X12.5.5,*]`	affected	generic	—
`[X12.6.1,*]`	affected	generic	—
`[X12.6.2,*]`	affected	generic	—
`[X12.6.3,*]`	affected	generic	—
`[X12.6.4,*]`	affected	generic	—
`[X12.7.0,*]`	affected	generic	—
`[X12.7.1,*]`	affected	generic	—
`[X14.0.0,*]`	affected	generic	—
`[X14.0.1,*]`	affected	generic	—
`[X14.0.2,*]`	affected	generic	—
`[X14.0.3,*]`	affected	generic	—
`[X14.0.4,*]`	affected	generic	—
`[X14.0.5,*]`	affected	generic	—
`[X14.0.6,*]`	affected	generic	—
`[X14.0.7,*]`	affected	generic	—
`[X14.0.8,*]`	affected	generic	—
`[X14.2.0,*]`	affected	generic	—
`[X14.0.9,*]`	affected	generic	—
`[X14.2.1,*]`	affected	generic	—
`[X14.2.2,*]`	affected	generic	—
`[X14.0.11,*]`	affected	generic	—
`[X14.2.5,*]`	affected	generic	—
`[X14.0.10,*]`	affected	generic	—
`[X14.2.6,*]`	affected	generic	—
`[X14.2.7,*]`	affected	generic	—
`[X14.3.0,*]`	affected	generic	—
`[X14.3.1,*]`	affected	generic	—
`[X14.3.2,*]`	affected	generic	—
`[X14.3.3,*]`	affected	generic	—
`[X15.0.0,*]`	affected	generic	—
`[X14.3.4,*]`	affected	generic	—
`[X14.3.5,*]`	affected	generic	—
`[X15.0.1,*]`	affected	generic	—
`[X15.0.2,*]`	affected	generic	—
`[X15.0.3,*]`	affected	generic	—
`[X14.3.6,*]`	affected	generic	—
`[X15.2.0,*]`	affected	generic	—
`[X15.2.1,*]`	affected	generic	—
`[X15.2.2,*]`	affected	generic	—
`[X15.2.3,*]`	affected	generic	—
`[X14.3.7,*]`	affected	generic	—
`[X15.2.4.,*]`	affected	generic	—
`[X15.2.4,*]`	affected	generic	—
`[X15.3.0,*]`	affected	generic	—
`[X15.3.1,*]`	affected	generic	—
`[X15.3.2,*]`	affected	generic	—
`[X15.4.0,*]`	affected	generic	—
`[X15.5.0,*]`	affected	generic	—
`[X15.5.1,*]`	affected	generic	—
`[X15.5.2,*]`	affected	generic	—

Found an issue or want to improve our Enrichment? You can suggest it directly by opening an issue on our dedicated GitHub repository .

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Apply the Cisco Expressway Series hardening release that addresses the out‑of‑bounds write vulnerabilities.
If a patch is not immediately available, restrict network access to the Expressway server by limiting inbound traffic to trusted networks or by implementing firewall rules that block unused ports.
Enable logging and monitoring for anomalous crashes or abnormal memory access, and investigate related alerts to detect potential exploitation attempts.

Generated by OpenCVE AI on October 22, 2026 at 04:58 UTC.

Tracking

Sign in to view the affected projects.

Advisories

No advisories yet.

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Changed

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.

The EPSS score is 0.00448.

Exploitation none

Automatable yes

Technical Impact partial

References

Link	Providers
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-exwy-hardening-FhcqBVcs
https://www.cve.org/Media/News/item/blog/2026/06/16/Preserving-Vulnerability-Level-Identification

History

Sat, 07 Nov 2026 18:30:00 +0000

Type	Values Removed	Values Added
References		https://www.cve.org/Media/News/item/blog/2026/06/16/Preserving-Vulnerability-Level-Identification

Thu, 22 Oct 2026 15:30:00 +0000

Type	Values Removed	Values Added
First Time appeared		Cisco Cisco expressway Series
Vendors & Products		Cisco Cisco expressway Series

Thu, 22 Oct 2026 14:30:00 +0000

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}`

Wed, 21 Oct 2026 17:15:00 +0000

Type	Values Removed	Values Added
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-2026-76490 are related to issues concerning out-of-bounds writes that are grouped under the Common Weakness Enumeration (CWE) Base CWE-787.
Title		Cisco Expressway Series Software Hardening Release: October 2026 - Out-of-bounds Write Vulnerabilities
Weaknesses		CWE-787
References		https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-exwy-hardening-FhcqBVcs
Metrics		cvssV3_1 `{'score': 8.6, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H'}`

Subscriptions

Cisco Expressway Series

MITRE

Status: PUBLISHED

Assigner: cisco

Published: 2026-10-21T16:17:29.557Z

Updated: 2026-11-07T17:29:43.355Z

Reserved: 2026-08-19T12:02:03.640Z

Link: CVE-2026-76490

Vulnrichment

Updated: 2026-11-07T17:29:43.355Z

NVD

Status : Awaiting Analysis

Published: 2026-10-21T17:19:08.340

Modified: 2026-11-07T18:17:27.803

Link: CVE-2026-76490

Redhat

No data.

OpenCVE Enrichment

Updated: 2026-10-22T14:57:19Z

Weaknesses

CWE-787
Out-of-bounds Write

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Changed

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

Exploitation none

Automatable yes

Technical Impact partial

Subscriptions

JSON object

JSON object

JSON object

JSON object

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