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.
- Published
- Oct 7, 2026
- Updated
- Oct 9, 2026
- EPSS
- 0.3% · 22th percentile
- CWE
- CWE-787
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Report tools
Action score
39
Monitor
Low priority for now.
- CVSS
- 39 / 40 · 9.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.3%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 9.8
- CNA · cisco
- 9.8
- agree
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
—
Versions reported by the vendor
Affected version ranges reported by the assigning authority (cisco). Independent of NVD's CPE analysis and usually ahead of it.
Cisco Cisco NX-OS Software
- 8.2(5), 7.3(5)D1(1), 8.4(2), 8.4(3), 9.2(3), 8.2(1), 7.3(1)D1(1), 9.2(2v), 7.3(0)D1(1), 7.3(4)D1(1), 9.2(1), 9.2(2t) … (+28)affected
Cisco Cisco NX-OS System Software in ACI Mode
- 15.2(1g), 15.2(2e), 15.2(2f), 15.2(2g), 15.2(2h), 15.2(3f), 15.2(3e), 15.2(3g), 15.2(4d), 15.2(4e), 15.2(5c), 15.2(5d) … (+28)affected
Cisco Cisco Unified Computing System (Managed)
- 4.0(1a), 4.1(1d), 4.0(4f), 4.0(4c), 4.0(2b), 4.1(2a), 4.0(4a), 4.0(4e), 4.0(4h), 4.0(2a), 4.1(1c), 4.0(1b) … (+28)affected
Same product
cisco: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-76501Cisco Nexus 9000 Series Switches SRv6 OAM (NGOAM) Remote Code Execution Vulnerability39Monitor
- CVE-2026-76486Cisco Nexus 3000 and 9000 Series Switches VXLAN OAM (NGOAM) Remote Code Execution Vulnerability39Monitor
- CVE-2026-76485Cisco Nexus 3000 and 9000 Series Switches VXLAN OAM (NGOAM) Remote Code Execution Vulnerability39Monitor
- CVE-2026-76471Cisco NX-OS Software NX-API Remote Code Execution Vulnerability39Monitor
- CVE-2026-76465Cisco Nexus 3000 and 9000 Series Switches MPLS OAM Remote Code Execution Vulnerability39Monitor
- CVE-2026-76455Cisco NX-OS Software Security Hardening Release: October 2026 - Improper Access Control Vulnerabilities39Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-26-1267 · Oct 8, 2026(Cisco Çoklu Ürün Güvenlik Bildirimi)
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-787 · Out-of-bounds WriteCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- CVSS8.8 → 9.8
- Severityhigh → critical
- Exploit maturity— → none
For records you follow, these changes also arrive as notifications. →
References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.