# CVE-2026-20058: Cisco Secure Firewall Threat Defense Software Snort 3 Visual Basic for Application Denial of Service Vulnerability

> Remote attackers can crash the Snort 3 Detection Engine by sending crafted VBA data, causing a denial of service on Cisco Secure Firewall Threat Defense devices.

- **Severity:** Medium 5.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 4 Mar 2026
- **Updated:** 4 Mar 2026
- **Also known as:** GHSA-q3px-v248-7pc3

## What is CVE-2026-20058?

CVE-2026-20058 is a medium-severity denial of service vulnerability in Cisco Secure Firewall Threat Defense, published on 4 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Multiple Cisco products are affected by vulnerabilities in the Snort 3 VBA feature that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to crash.

These vulnerabilities are due to improper error checking when decompressing VBA data. An attacker could exploit these vulnerabilities by sending crafted VBA data to the Snort 3 Detection Engine on the targeted device. A successful exploit could allow the attacker to cause the Snort 3 Detection Engine to unexpectedly restart, causing a DoS condition.

Weakness: CWE-786 (Access of Memory Location Before Start of Buffer)

## Which versions are affected by CVE-2026-20058?

It affects 3 products.


Products: Cisco Secure Firewall Threat Defense, Cisco Snort, Cisco Unified Threat Defense Snort Intrusion Prevention System Engine.

## How do I fix CVE-2026-20058?

No fix has been published for CVE-2026-20058 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-20058 being exploited?

There is no known exploitation of CVE-2026-20058 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Secure Firewall Threat Defense

- [CVE-2024-20412](https://insights.sbomify.com/CVE-2024-20412/): Hardcoded credentials in Cisco Firepower Threat Defense Software (critical 9.3)
- [CVE-2024-20330](https://insights.sbomify.com/CVE-2024-20330/): Memory corruption in Cisco Firepower Threat Defense Software (high 8.6)
- [CVE-2024-20339](https://insights.sbomify.com/CVE-2024-20339/): Cisco Firepower Threat Defense Software for Firepower 2100 Series TLS Denial of Service Vulnerability (high 8.6)
- [CVE-2024-20351](https://insights.sbomify.com/CVE-2024-20351/): Cisco Firepower Threat Defense Software Snort Firewall Denial of Service Vulnerability (high 8.6)
- [CVE-2023-20083](https://insights.sbomify.com/CVE-2023-20083/): Denial of service in Cisco Firepower Threat Defense Software (high 8.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-20058 and fix it if it is affected.

What it is: CVE-2026-20058 is a medium-severity denial of service vulnerability in Cisco Secure Firewall Threat Defense, published on 4 Mar 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-2026-20058 in the wild and no public exploit code.

Affected product: Cisco Secure Firewall Threat Defense. 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-2026-20058/ (Markdown: https://insights.sbomify.com/CVE-2026-20058/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-20058
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-20058
- OSV: https://osv.dev/vulnerability/CVE-2026-20058

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-20058/
Summaries are generated and may contain mistakes; the official description above is the record.