# CVE-2020-3556: Cisco AnyConnect Secure Mobility Client Arbitrary Code Execution Vulnerability > An authenticated local attacker can execute arbitrary code by sending crafted messages to the unauthenticated IPC listener of the Cisco AnyConnect client. - **Severity:** High 7.3 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** A user has to click or open something - **Fix available:** No - **Published:** 6 Nov 2020 - **Updated:** 13 Nov 2024 - **Also known as:** GHSA-v6p8-gw74-vfg4 ## What is CVE-2020-3556? CVE-2020-3556 is a high-severity missing authorization vulnerability in Cisco Anyconnect Secure Mobility Client, published on 6 Nov 2020. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link. ### Official description A vulnerability in the interprocess communication (IPC) channel of Cisco AnyConnect Secure Mobility Client Software could allow an authenticated, local attacker to cause a targeted AnyConnect user to execute a malicious script. The vulnerability is due to a lack of authentication to the IPC listener. An attacker could exploit this vulnerability by sending crafted IPC messages to the AnyConnect client IPC listener. A successful exploit could allow an attacker to cause the targeted AnyConnect user to execute a script. This script would execute with the privileges of the targeted AnyConnect user. In order to successfully exploit this vulnerability, there must be an ongoing AnyConnect session by the targeted user at the time of the attack. To exploit this vulnerability, the attacker would also need valid user credentials on the system upon which the AnyConnect client is being run. Cisco has not released software updates that address this vulnerability. Weakness: CWE-20 (Improper Input Validation) ## Which versions are affected by CVE-2020-3556? It affects 1 product. Products: Cisco Anyconnect Secure Mobility Client. ## How do I fix CVE-2020-3556? No fix has been published for CVE-2020-3556 yet. Limit exposure of the affected software until one is available. ## Is CVE-2020-3556 being exploited? There is no known exploitation of CVE-2020-3556 in the wild and no public exploit code. ## Other vulnerabilities in Cisco Anyconnect Secure Mobility Client - [CVE-2020-3433](https://insights.sbomify.com/CVE-2020-3433/): Cisco AnyConnect Secure Mobility Client for Windows DLL Hijacking (high 7.8, exploited in the wild) - [CVE-2020-3153](https://insights.sbomify.com/CVE-2020-3153/): Cisco AnyConnect Secure Mobility Client for Windows Uncontrolled Search Path (medium 6.5, exploited in the wild) - [CVE-2012-3088](https://insights.sbomify.com/CVE-2012-3088/): Security feature bypass in n/a (critical 9.3) - [CVE-2012-2493](https://insights.sbomify.com/CVE-2012-2493/): Code injection in n/a (critical 9.3) - [CVE-2011-2040](https://insights.sbomify.com/CVE-2011-2040/): Code injection in n/a (critical 9.3) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2020-3556 and fix it if it is affected. What it is: CVE-2020-3556 is a high-severity missing authorization vulnerability in Cisco Anyconnect Secure Mobility Client, published on 6 Nov 2020. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link. Exploitation: There is no known exploitation of CVE-2020-3556 in the wild and no public exploit code. Affected product: Cisco Anyconnect Secure Mobility Client. 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-2020-3556/ (Markdown: https://insights.sbomify.com/CVE-2020-3556/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2020-3556 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-3556 - OSV: https://osv.dev/vulnerability/CVE-2020-3556 --- From sbomify Insights: https://insights.sbomify.com/CVE-2020-3556/ Summaries are generated and may contain mistakes; the official description above is the record.