CVE-2026-76459 - Vulnerability Details

- Cisco NX-OS Software Security 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 NX-OS engineering team has conducted a comprehensive internal security review. This review resulted in a software hardening release that addresses multiple internally discovered vulnerabilities.

The vulnerabilities tracked by CVE-2026-76459 are related to out-of-bounds write issues that are grouped under the Common Weakness Enumeration (CWE) CWE-787.

Published: 2026-10-07

Score: 9.8 Critical

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

The vulnerability identified as CVE‑2026‑76459 arises from an out‑of‑bounds write in Cisco NX‑OS software, which could corrupt memory on affected devices and potentially enable an attacker to execute arbitrary code or elevate privileges. The weakness is classified as CWE‑787, indicating that data is written beyond the bounds of a buffer. While the advisory does not provide specific details on the memory location or the payload structure, the nature of the flaw suggests that a carefully crafted input could overwrite control data in memory.

Affected Systems

The flaw affects Cisco NX‑OS Software, Cisco NX‑OS System Software in ACI Mode, and Cisco Unified Computing System (Managed). No specific version numbers are enumerated in the advisory; administrators should verify whether their devices run any NX‑OS software that may have been impacted by this internal review.

Risk and Exploitability

The CVSS score is 9.8, indicating a high severity level. The EPSS score of < 1% indicates a low probability of exploitation in the wild. The vulnerability is not listed in the CISA KEV catalog. Based on the description, it is inferred that an attacker would need network access to a vulnerable device and would likely craft a payload that triggers the memory corruption; the exact attack vector is not disclosed, but the risk remains high until the patch is applied.

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 NX-OS Software

unknown

Version	Status	Constraints
`8.2(5)`	affected	—
`7.3(5)D1(1)`	affected	—
`8.4(2)`	affected	—
`8.4(3)`	affected	—
`9.2(3)`	affected	—
`8.2(1)`	affected	—
`7.3(1)D1(1)`	affected	—
`9.2(2v)`	affected	—
`7.3(0)D1(1)`	affected	—
`7.3(4)D1(1)`	affected	—
`9.2(1)`	affected	—
`9.2(2t)`	affected	—
`9.2(3y)`	affected	—
`9.3(2)`	affected	—
`7.3(1)DY(1)`	affected	—
`8.1(1)`	affected	—
`8.2(2)`	affected	—
`8.3(2)`	affected	—
`7.3(2)D1(3a)`	affected	—
`9.2(4)`	affected	—
`8.1(2)`	affected	—
`7.3(3)D1(1)`	affected	—
`8.2(3)`	affected	—
`8.3(1)`	affected	—
`8.4(1)`	affected	—
`8.1(1b)`	affected	—
`7.3(0)DX(1)`	affected	—
`7.3(2)D1(1)`	affected	—
`9.3(1)`	affected	—
`7.3(2)D1(2)`	affected	—
`8.2(4)`	affected	—
`7.3(0)DY(1)`	affected	—
`9.3(1z)`	affected	—
`9.2(2)`	affected	—
`8.1(2a)`	affected	—
`7.3(2)D1(3)`	affected	—
`8.1(1a)`	affected	—
`8.4(1a)`	affected	—
`9.3(3)`	affected	—
`7.3(2)D1(1d)`	affected	—
`9.3(4)`	affected	—
`7.3(6)D1(1)`	affected	—
`8.2(6)`	affected	—
`9.3(5)`	affected	—
`8.4(2a)`	affected	—
`8.4(2b)`	affected	—
`8.5(1)`	affected	—
`9.3(6)`	affected	—
`8.4(4)`	affected	—
`7.3(7)D1(1)`	affected	—
`8.4(2c)`	affected	—
`9.3(5w)`	affected	—
`8.2(7)`	affected	—
`9.3(7)`	affected	—
`9.3(7k)`	affected	—
`7.3(8)D1(1)`	affected	—
`9.3(7a)`	affected	—
`8.2(7a)`	affected	—
`9.3(8)`	affected	—
`8.4(4a)`	affected	—
`8.4(2d)`	affected	—
`8.4(5)`	affected	—
`8.2(8)`	affected	—
`9.3(9)`	affected	—
`7.3(9)D1(1)`	affected	—
`8.4(6)`	affected	—
`8.4(2e)`	affected	—
`9.3(10)`	affected	—
`9.2(1a)`	affected	—
`8.2(9)`	affected	—
`10.3(1)`	affected	—
`8.4(7)`	affected	—
`10.3(2)`	affected	—
`8.4(6a)`	affected	—
`9.3(11)`	affected	—
`10.3(3)`	affected	—
`9.4(1)`	affected	—
`9.3(2a)`	affected	—
`8.4(2f)`	affected	—
`8.2(10)`	affected	—
`9.3(12)`	affected	—
`10.4(1)`	affected	—
`8.4(8)`	affected	—
`10.3(99w)`	affected	—
`10.3(3w)`	affected	—
`10.3(99x)`	affected	—
`10.3(3o)`	affected	—
`8.4(9)`	affected	—
`10.3(4)`	affected	—
`10.3(3p)`	affected	—
`10.3(4a)`	affected	—
`9.4(1a)`	affected	—
`10.4(2)`	affected	—
`10.3(3q)`	affected	—
`9.3(13)`	affected	—
`8.2(11)`	affected	—
`9.4(2)`	affected	—
`10.3(5)`	affected	—
`10.4(3)`	affected	—
`10.3(3x)`	affected	—
`10.3(4g)`	affected	—
`10.5(1)`	affected	—
`8.4(10)`	affected	—
`9.4(2a)`	affected	—
`10.3(3r)`	affected	—
`10.3(6)`	affected	—
`9.3(14)`	affected	—
`10.4(4)`	affected	—
`10.3(4h)`	affected	—
`10.5(2)`	affected	—
`10.5(1j)`	affected	—
`8.4(11)`	affected	—
`9.4(3)`	affected	—
`10.3(7)`	affected	—
`10.4(5)`	affected	—
`10.5(3)`	affected	—
`9.3(15)`	affected	—
`9.4(3a)`	affected	—
`10.4(4g)`	affected	—
`10.5(4)`	affected	—
`9.4(3b)`	affected	—
`8.4(12)`	affected	—
`10.6(1)`	affected	—
`10.5(3t)`	affected	—
`10.3(8)`	affected	—
`10.4(6)`	affected	—
`10.5(3s)`	affected	—
`10.5(3e)`	affected	—
`9.4(4)`	affected	—
`10.5(3o)`	affected	—
`9.3(16)`	affected	—
`10.6(1s)`	affected	—
`10.6(2)`	affected	—
`10.5(3p)`	affected	—
`9.4(5)`	affected	—
`10.3(9)`	affected	—
`10.6(2s)`	affected	—
`8.4(13)`	affected	—
`10.6(3)`	affected	—
`10.4(7)`	affected	—
`10.5(5)`	affected	—
`9.3(17)`	affected	—
`10.6(2n)`	affected	—
`10.6(3q)`	affected	—
`10.6(3o)`	affected	—
`10.6(3s)`	affected	—

Cisco

Cisco NX-OS System Software in ACI Mode

unknown

Version	Status	Constraints
`15.2(1g)`	affected	—
`15.2(2e)`	affected	—
`15.2(2f)`	affected	—
`15.2(2g)`	affected	—
`15.2(2h)`	affected	—
`15.2(3f)`	affected	—
`15.2(3e)`	affected	—
`15.2(3g)`	affected	—
`15.2(4d)`	affected	—
`15.2(4e)`	affected	—
`15.2(5c)`	affected	—
`15.2(5d)`	affected	—
`16.0(1g)`	affected	—
`15.2(5e)`	affected	—
`15.2(4f)`	affected	—
`15.2(6e)`	affected	—
`15.2(6h)`	affected	—
`16.0(1j)`	affected	—
`15.2(6g)`	affected	—
`15.2(7f)`	affected	—
`15.2(7g)`	affected	—
`16.0(2h)`	affected	—
`15.2(8d)`	affected	—
`16.0(2j)`	affected	—
`15.2(8e)`	affected	—
`16.0(3d)`	affected	—
`16.0(3e)`	affected	—
`15.2(8f)`	affected	—
`15.2(8g)`	affected	—
`15.3(1d)`	affected	—
`15.2(8h)`	affected	—
`16.0(4c)`	affected	—
`15.3(2a)`	affected	—
`15.2(8i)`	affected	—
`16.0(5h)`	affected	—
`15.3(2b)`	affected	—
`16.0(3g)`	affected	—
`16.0(5j)`	affected	—
`15.3(2c)`	affected	—
`16.0(6c)`	affected	—
`15.3(2d)`	affected	—
`16.1(1f)`	affected	—
`16.0(7e)`	affected	—
`16.0(8e)`	affected	—
`15.3(2e)`	affected	—
`16.0(8f)`	affected	—
`16.1(2f)`	affected	—
`16.1(2g)`	affected	—
`15.3(2f)`	affected	—
`16.0(9c)`	affected	—
`16.1(3f)`	affected	—
`16.0(9d)`	affected	—
`16.0(6h)`	affected	—
`16.0(8h)`	affected	—
`16.1(3g)`	affected	—
`16.0(9e)`	affected	—
`16.1(4h)`	affected	—
`16.1(5e)`	affected	—
`16.2(1g)`	affected	—
`16.0(9f)`	affected	—
`16.2(2e)`	affected	—

Cisco

Cisco Unified Computing System (Managed)

unknown

Version	Status	Constraints
`4.0(1a)`	affected	—
`4.1(1d)`	affected	—
`4.0(4f)`	affected	—
`4.0(4c)`	affected	—
`4.0(2b)`	affected	—
`4.1(2a)`	affected	—
`4.0(4a)`	affected	—
`4.0(4e)`	affected	—
`4.0(4h)`	affected	—
`4.0(2a)`	affected	—
`4.1(1c)`	affected	—
`4.0(1b)`	affected	—
`4.1(1e)`	affected	—
`4.0(4d)`	affected	—
`4.0(4b)`	affected	—
`4.0(2e)`	affected	—
`4.1(1a)`	affected	—
`4.0(4g)`	affected	—
`4.0(1d)`	affected	—
`4.0(1c)`	affected	—
`4.0(4i)`	affected	—
`4.0(2d)`	affected	—
`4.1(1b)`	affected	—
`4.1(2b)`	affected	—
`4.0(4k)`	affected	—
`4.1(3a)`	affected	—
`4.1(3b)`	affected	—
`4.1(2c)`	affected	—
`4.0(4l)`	affected	—
`4.1(4a)`	affected	—
`4.1(3c)`	affected	—
`4.1(3d)`	affected	—
`4.2(1c)`	affected	—
`4.2(1d)`	affected	—
`4.0(4m)`	affected	—
`4.1(3e)`	affected	—
`4.2(1f)`	affected	—
`4.1(3f)`	affected	—
`4.2(1i)`	affected	—
`4.1(3h)`	affected	—
`4.2(1k)`	affected	—
`4.2(1l)`	affected	—
`4.0(4n)`	affected	—
`4.2(1m)`	affected	—
`4.1(3i)`	affected	—
`4.2(2a)`	affected	—
`4.2(1n)`	affected	—
`4.1(3j)`	affected	—
`4.2(2c)`	affected	—
`4.2(2d)`	affected	—
`4.2(3b)`	affected	—
`4.1(3k)`	affected	—
`4.0(4o)`	affected	—
`4.2(2e)`	affected	—
`4.2(3d)`	affected	—
`4.2(3e)`	affected	—
`4.2(3g)`	affected	—
`4.1(3l)`	affected	—
`4.3(2b)`	affected	—
`4.2(3h)`	affected	—
`4.2(3i)`	affected	—
`4.3(2c)`	affected	—
`4.1(3m)`	affected	—
`4.3(2e)`	affected	—
`4.3(3a)`	affected	—
`4.2(3j)`	affected	—
`4.3(3c)`	affected	—
`4.3(4a)`	affected	—
`4.2(3k)`	affected	—
`4.3(4b)`	affected	—
`4.3(4c)`	affected	—
`4.2(3l)`	affected	—
`4.3(4d)`	affected	—
`4.3(2f)`	affected	—
`4.2(3m)`	affected	—
`4.3(5a)`	affected	—
`4.3(4e)`	affected	—
`4.1(3n)`	affected	—
`4.3(4f)`	affected	—
`4.2(3n)`	affected	—
`4.3(5c)`	affected	—
`4.2(3o)`	affected	—
`4.3(5d)`	affected	—
`4.3(6a)`	affected	—
`4.3(6b)`	affected	—
`4.3(5e)`	affected	—
`4.3(6c)`	affected	—
`4.2(3p)`	affected	—
`6.0(1b)`	affected	—
`6.0(1c)`	affected	—
`4.3(6d)`	affected	—
`6.0(1d)`	affected	—
`6.0(1e)`	affected	—
`4.3(6e)`	affected	—
`6.0(1f)`	affected	—
`4.3(6f)`	affected	—
`6.0(2b)`	affected	—
`6.0(1h)`	affected	—
`4.2(3r)`	affected	—
`6.0(2c)`	affected	—
`4.3(6g)`	affected	—
`6.0(2d)`	affected	—
`4.3(6h)`	affected	—
`4.2(3s)`	affected	—
`4.3(6i)`	affected	—

No data.

No data available yet.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Deploy the Cisco NX‑OS security hardening release that includes the CVE‑2026‑76459 fix.
Reboot or restart affected NX‑OS services so that the patched code paths are active.
Temporarily restrict external access to the management interfaces of NX‑OS devices until the hardening release is fully deployed and verified.

Generated by OpenCVE AI on October 9, 2026 at 15:59 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 Unchanged

Confidentiality Impact High

Integrity Impact High

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 0.00307.

Exploitation none

Automatable no

Technical Impact total

References

Link	Providers
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-nxosw1-cWzSbtR

History

Fri, 09 Oct 2026 13:30:00 +0000

Type	Values Removed	Values Added
Metrics	cvssV3_1 `{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}`	cvssV3_1 `{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}`

Wed, 07 Oct 2026 18:30:00 +0000

Type	Values Removed	Values Added
Metrics		ssvc `{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}`

Wed, 07 Oct 2026 16:30:00 +0000

Type	Values Removed	Values Added
Description		As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco NX-OS engineering team has conducted a comprehensive internal security review. This review resulted in a software hardening release that addresses multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-76459 are related to out-of-bounds write issues that are grouped under the Common Weakness Enumeration (CWE) CWE-787.
Title		Cisco NX-OS Software Security Hardening Release: October 2026 - Out-of-bounds Write Vulnerabilities
Weaknesses		CWE-787
References		https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hardening-nxosw1-cWzSbtR
Metrics		cvssV3_1 `{'score': 8.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}`

Subscriptions

No data.

MITRE

Status: PUBLISHED

Assigner: cisco

Published: 2026-10-07T16:15:43.747Z

Updated: 2026-10-09T13:07:32.625Z

Reserved: 2026-08-19T12:02:03.637Z

Link: CVE-2026-76459

Vulnrichment

Updated: 2026-10-07T16:50:23.089Z

NVD

Status : Awaiting Analysis

Published: 2026-10-07T17:16:58.553

Modified: 2026-10-09T14:17:22.427

Link: CVE-2026-76459

Redhat

No data.

OpenCVE Enrichment

Updated: 2026-10-09T16:00:10Z

Weaknesses

CWE-787
Out-of-bounds Write

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

Exploitation none

Automatable no

Technical Impact total

Subscriptions

JSON object

JSON object

JSON object

JSON object

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