# CVE-2019-12677: Cisco Adaptive Security Appliance Software SSL VPN Denial of Service Vulnerability > Authenticated remote attackers can cause a denial of service by opening many SSL VPN sessions, preventing new SSL/TLS connections until the device is reloaded. - **Severity:** High 7.7 (`CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** No - **Published:** 2 Oct 2019 - **Updated:** 21 Nov 2024 - **Also known as:** GHSA-wvvv-6xf9-8f8r ## What is CVE-2019-12677? CVE-2019-12677 is a high-severity denial of service vulnerability in Cisco Adaptive Security Appliance Software, published on 2 Oct 2019. Any signed-in user can exploit it over the network, with no action from the victim. ### Official description A vulnerability in the Secure Sockets Layer (SSL) VPN feature of Cisco Adaptive Security Appliance (ASA) Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition that prevents the creation of new SSL/Transport Layer Security (TLS) connections to an affected device. The vulnerability is due to incorrect handling of Base64-encoded strings. An attacker could exploit this vulnerability by opening many SSL VPN sessions to an affected device. The attacker would need to have valid user credentials on the affected device to exploit this vulnerability. A successful exploit could allow the attacker to overwrite a special system memory location, which will eventually result in memory allocation errors for new SSL/TLS sessions to the device, preventing successful establishment of these sessions. A reload of the device is required to recover from this condition. Established SSL/TLS connections to the device and SSL/TLS connections through the device are not affected. Note: Although this vulnerability is in the SSL VPN feature, successful exploitation of this vulnerability would affect all new SSL/TLS sessions to the device, including management sessions. Weakness: CWE-755 (Improper Handling of Exceptional Conditions), CWE-172 (Improper Encoding or Decoding of Data) ## Which versions are affected by CVE-2019-12677? It affects 1 product. Products: Cisco Adaptive Security Appliance Software. ## How do I fix CVE-2019-12677? No fix has been published for CVE-2019-12677 yet. Limit exposure of the affected software until one is available. ## Is CVE-2019-12677 being exploited? There is no known exploitation of CVE-2019-12677 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-2019-12677 and fix it if it is affected. What it is: CVE-2019-12677 is a high-severity denial of service vulnerability in Cisco Adaptive Security Appliance Software, published on 2 Oct 2019. Any signed-in user can exploit it over the network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2019-12677 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-2019-12677/ (Markdown: https://insights.sbomify.com/CVE-2019-12677/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2019-12677 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-12677 - OSV: https://osv.dev/vulnerability/CVE-2019-12677 --- From sbomify Insights: https://insights.sbomify.com/CVE-2019-12677/ Summaries are generated and may contain mistakes; the official description above is the record.