# CVE-2006-3906: Denial of service in n/a

> Remote attackers can cause denial of service on Cisco IOS, VPN 3000, and PIX firewalls by flooding IKE Phase-1 packets, exhausting resources.

- **Severity:** Medium 5.0 (`AV:N/AC:L/Au:N/C:N/I:N/A:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 Jul 2006
- **Updated:** 7 Aug 2024
- **Also known as:** GHSA-v43w-r88q-4mh9

## What is CVE-2006-3906?

CVE-2006-3906 is a medium-severity denial of service vulnerability in Cisco Adaptive Security Appliance Software, published on 27 Jul 2006. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Internet Key Exchange (IKE) version 1 protocol, as implemented on Cisco IOS, VPN 3000 Concentrators, and PIX firewalls, allows remote attackers to cause a denial of service (resource exhaustion) via a flood of IKE Phase-1 packets that exceed the session expiration rate. NOTE: it has been argued that this is due to a design weakness of the IKE version 1 protocol, in which case other vendors and implementations would also be affected.

## Which versions are affected by CVE-2006-3906?

It affects 21 products.


Products: Cisco Adaptive Security Appliance Software, Cisco Ios, Cisco Pix Asa Ids, Cisco Pix Firewall, Cisco Pix Firewall 501, Cisco Pix Firewall 506, Cisco Pix Firewall 515, Cisco Pix Firewall 515e, Cisco Pix Firewall 520, Cisco Pix Firewall 525, Cisco Pix Firewall 535, Cisco Pix Firewall Software, Cisco Secure Pix Firewall, Cisco Vpn 3000 Concentrator Series Software, Cisco Vpn 3001 Concentrator, Cisco Vpn 3005 Concentrator Software, Cisco Vpn 3015 Concentrator, Cisco Vpn 3020 Concentrator, Cisco Vpn 3030 Concentator, Cisco Vpn 3060 Concentrator and 1 more.

## How do I fix CVE-2006-3906?

No fix has been published for CVE-2006-3906 yet. Limit exposure of the affected software until one is available.

## Is CVE-2006-3906 being exploited?

There is no known exploitation of CVE-2006-3906 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Adaptive Security Appliance Software

- [CVE-2025-20333](https://insights.sbomify.com/CVE-2025-20333/): Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Buffer Overflow (critical 9.9, exploited in the wild)
- [CVE-2016-6366](https://insights.sbomify.com/CVE-2016-6366/): Cisco Adaptive Security Appliance (ASA) SNMP Buffer Overflow (high 8.8, exploited in the wild)
- [CVE-2026-20349](https://insights.sbomify.com/CVE-2026-20349/): Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection (high 8.6, exploited in the wild)
- [CVE-2024-20353](https://insights.sbomify.com/CVE-2024-20353/): Cisco ASA and FTD Denial of Service (high 8.6, exploited in the wild)
- [CVE-2016-6367](https://insights.sbomify.com/CVE-2016-6367/): Cisco Adaptive Security Appliance (ASA) CLI Remote Code Execution (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2006-3906 and fix it if it is affected.

What it is: CVE-2006-3906 is a medium-severity denial of service vulnerability in Cisco Adaptive Security Appliance Software, published on 27 Jul 2006. 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-2006-3906 in the wild and no public exploit code.

Affected product: Cisco Adaptive Security Appliance Software. 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-2006-3906/ (Markdown: https://insights.sbomify.com/CVE-2006-3906/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2006-3906
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2006-3906
- OSV: https://osv.dev/vulnerability/CVE-2006-3906

---
From sbomify Insights: https://insights.sbomify.com/CVE-2006-3906/
Summaries are generated and may contain mistakes; the official description above is the record.