# CVE-2026-76439: Cisco Identity Services Engine Event Injection Vulnerability

> Unauthenticated attackers can manipulate endpoint posture status by exploiting insufficient authentication on the guest portal interface.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Sep 2026
- **Updated:** 18 Sep 2026
- **Also known as:** GHSA-ppcr-3wc7-2p22

## What is CVE-2026-76439?

CVE-2026-76439 is a medium-severity missing authorization vulnerability in Cisco Identity Services Engine, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the endpoint posture status reporting functionality of the guest portal web application of Cisco ISE could allow an unauthenticated, remote attacker to submit forged posture status events into the endpoint posture pipeline.

This vulnerability is due to insufficient authentication on an internal interface that is exposed through the guest portal. An attacker could exploit this vulnerability by sending a crafted request to an affected system. A successful exploit could allow the attacker to manipulate the posture status on the affected system.

Weakness: CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2026-76439?

It affects 2 products.


Products: Cisco Identity Services Engine, Cisco Identity Services Engine Passive Identity Connector.

## How do I fix CVE-2026-76439?

No fix has been published for CVE-2026-76439 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-76439 being exploited?

There is no known exploitation of CVE-2026-76439 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Identity Services Engine

- [CVE-2026-76460](https://insights.sbomify.com/CVE-2026-76460/): Cisco Identity Services Engine Incorrect Use of Privileged APIs (critical 10.0, exploited in the wild)
- [CVE-2025-20337](https://insights.sbomify.com/CVE-2025-20337/): Cisco Identity Services Engine Injection (critical 10.0, exploited in the wild)
- [CVE-2025-20281](https://insights.sbomify.com/CVE-2025-20281/): Cisco Identity Services Engine Injection (critical 10.0, exploited in the wild)
- [CVE-2026-20130](https://insights.sbomify.com/CVE-2026-20130/): Cisco Identity Services Engine Hardening Release - Improper Neutralization Vulnerabilities (critical 10.0)
- [CVE-2026-20192](https://insights.sbomify.com/CVE-2026-20192/): Cisco Identity Services Engine Hardening Release - Access Control Vulnerabilities (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-76439 and fix it if it is affected.

What it is: CVE-2026-76439 is a medium-severity missing authorization vulnerability in Cisco Identity Services Engine, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-76439 in the wild and no public exploit code.

Affected product: Cisco Identity Services Engine. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-76439/ (Markdown: https://insights.sbomify.com/CVE-2026-76439/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-76439
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-76439
- OSV: https://osv.dev/vulnerability/CVE-2026-76439

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-76439/
Summaries are generated and may contain mistakes; the official description above is the record.