CVE-2026-76459: Cisco NX-OS Software Security Hardening Release: October 2026 - Out-of-bounds Write Vulnerabilities
- Is it exploited?
Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.
- How likely is exploitation in the next 30 days?
- 0.3%
EPSS score, percentile 23.5 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 9.8 Critical
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- 8.2(5)
- 7.3(5)D1(1)
- 8.4(2)
- 8.4(3)
- 9.2(3)
- 8.2(1)
and 30 more in the table below
Source: CISA KEV 2026.10.28, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
What to do
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | 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) |
Versions not listed are: unknown.
And 134 more version entries in the CVE record.
| Status | Versions |
|---|---|
| Affected | 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) |
Versions not listed are: unknown.
And 49 more version entries in the CVE record.
| Status | Versions |
|---|---|
| Affected | 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) |
Versions not listed are: unknown.
And 93 more version entries in the CVE record.
Source: CVE List, as of . About the data.
About this vulnerability
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…
Summary: CVE record, as of .
- CISA has not added CVE-2026-76459 to its Known Exploited Vulnerabilities (KEV) catalog, as of 28 Oct 2026.
- The CVE record was published on 7 Oct 2026.
- The CVE record carries a CVSS v3.1 base score of 9.8 (Critical), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.3% (percentile 23.5), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
- CISA's SSVC assessment in the CVE record: exploitation none, automatable no, technical impact total.
Source: CISA KEV 2026.10.28, as of ; CVE List, as of ; FIRST EPSS, as of . About the data.
Description
Cisco NX-OS Software Security Hardening Release: October 2026 - Out-of-bounds Write Vulnerabilities
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.
Source: CVE List, as of . About the data.
Weakness
CWE-787
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| CVE record last updated |
References
1
Known exploited Cisco vulnerabilities
- CVE-2026-76519: Cisco Secure Email Gateway Relative Path Traversal Vulnerability
- CVE-2026-76504: Cisco Catalyst SD-WAN Manager Hex Encoding Vulnerability
- CVE-2026-76460: Cisco Identity Services Engine Incorrect Use of Privileged APIs Vulnerability
- CVE-2026-76461: Cisco Secure Email Gateway SQL Injection Vulnerability
- CVE-2026-20079: Cisco Firewall Management Center Authentication Bypass Using an Alternate Path or Channel Vulnerability