# CVE-2019-15256: Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software IKEv1 Denial of Service Vulnerability

> Unauthenticated remote attackers can cause a denial of service by sending malicious IKEv1 traffic to Cisco ASA or FTD devices, exhausting memory and triggering a reload.

- **Severity:** High 8.6 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 2 Oct 2019
- **Updated:** 19 Nov 2024
- **Also known as:** GHSA-5p28-46mx-rrvx

## What is CVE-2019-15256?

CVE-2019-15256 is a high-severity denial of service vulnerability in Cisco Adaptive Security Appliance Software, published on 2 Oct 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A vulnerability in the Internet Key Exchange version 1 (IKEv1) feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to trigger a reload of an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to improper management of system memory. An attacker could exploit this vulnerability by sending malicious IKEv1 traffic to an affected device. The attacker does not need valid credentials to authenticate the VPN session, nor does the attacker's source address need to match a peer statement in the crypto map applied to the ingress interface of the affected device. An exploit could allow the attacker to exhaust system memory resources, leading to a reload of an affected device.

Weakness: CWE-400 (Uncontrolled Resource Consumption), CWE-399

## Which versions are affected by CVE-2019-15256?

It affects 13 products.


Products: Cisco Adaptive Security Appliance Software, Cisco Asa 5505 Firmware, Cisco Asa 5510 Firmware, Cisco Asa 5512-X Firmware, Cisco Asa 5515-X Firmware, Cisco Asa 5520 Firmware, Cisco Asa 5525-X Firmware, Cisco Asa 5540 Firmware, Cisco Asa 5545-X Firmware, Cisco Asa 5550 Firmware, Cisco Asa 5555-X Firmware, Cisco Asa 5580 Firmware, Cisco Secure Firewall Threat Defense.

## How do I fix CVE-2019-15256?

No fix has been published for CVE-2019-15256 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-15256 being exploited?

There is no known exploitation of CVE-2019-15256 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-2019-15256 and fix it if it is affected.

What it is: CVE-2019-15256 is a high-severity denial of service vulnerability in Cisco Adaptive Security Appliance Software, published on 2 Oct 2019. 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-2019-15256 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-2019-15256/ (Markdown: https://insights.sbomify.com/CVE-2019-15256/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-15256
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-15256
- OSV: https://osv.dev/vulnerability/CVE-2019-15256

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From sbomify Insights: https://insights.sbomify.com/CVE-2019-15256/
Summaries are generated and may contain mistakes; the official description above is the record.