# CVE-2020-25708: Denial of service in libvncserver > A malicious client can cause a denial of service in libvncserver by triggering a divide by zero error via a crafted message. - **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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:** Yes - **Published:** 27 Nov 2020 - **Updated:** 4 Aug 2024 - **Also known as:** DEBIAN-CVE-2020-25708, DLA-2451-1, GHSA-3xcq-6vjj-wqx7, MGASA-2020-0439, SUSE-SU-2020:14549-1, SUSE-SU-2020:3515-1, SUSE-SU-2020:3550-1, UBUNTU-CVE-2020-25708, USN-4636-1, openSUSE-SU-2020:2025-1, openSUSE-SU-2020:2097-1 ## What is CVE-2020-25708? CVE-2020-25708 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 27 Nov 2020. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description A divide by zero issue was found to occur in libvncserver-0.9.12. A malicious client could use this flaw to send a specially crafted message that, when processed by the VNC server, would lead to a floating point exception, resulting in a denial of service. Weakness: CWE-369 (Divide By Zero) ## Which versions are affected by CVE-2020-25708? It affects 3 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `LibVNCServer` | SUSE:Enterprise Storage 5 | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:HPE Helion OpenStack 8 | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:Linux Enterprise Module for Package Hub 15 SP1 | All versions | 0.9.10-4.25.1 | | `LibVNCServer` | SUSE:Linux Enterprise Module for Package Hub 15 SP2 | All versions | 0.9.10-4.25.1 | | `LibVNCServer` | SUSE:Linux Enterprise Point of Sale 11 SP3 | All versions | 0.9.1-160.22.1 | | `LibVNCServer` | SUSE:Linux Enterprise Server 11 SP4-LTSS | All versions | 0.9.1-160.22.1 | | `LibVNCServer` | SUSE:Linux Enterprise Server 12 SP2-BCL | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:Linux Enterprise Server 12 SP2-LTSS | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:Linux Enterprise Server 12 SP3-BCL | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:Linux Enterprise Server 12 SP3-LTSS | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:Linux Enterprise Server 12 SP4-LTSS | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:Linux Enterprise Server 12 SP5 | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:Linux Enterprise Server for SAP Applications 12 SP2 | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:Linux Enterprise Server for SAP Applications 12 SP3 | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:Linux Enterprise Server for SAP Applications 12 SP4 | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:Linux Enterprise Server for SAP Applications 12 SP5 | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:Linux Enterprise Software Development Kit 12 SP5 | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:Linux Enterprise Workstation Extension 15 SP1 | All versions | 0.9.10-4.25.1 | | `LibVNCServer` | SUSE:Linux Enterprise Workstation Extension 15 SP2 | All versions | 0.9.10-4.25.1 | | `LibVNCServer` | SUSE:OpenStack Cloud 7 | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:OpenStack Cloud 8 | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:OpenStack Cloud 9 | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:OpenStack Cloud Crowbar 8 | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | SUSE:OpenStack Cloud Crowbar 9 | All versions | 0.9.9-17.34.1 | | `LibVNCServer` | openSUSE:Leap 15.1 | All versions | 0.9.10-lp151.7.12.1 | | `LibVNCServer` | openSUSE:Leap 15.2 | All versions | 0.9.10-lp152.9.8.1 | Products: Debian Debian Linux, Libvncserver Project Libvncserver, Redhat Enterprise Linux. ## How do I fix CVE-2020-25708? Apply the vendor's patch. ## Is CVE-2020-25708 being exploited? There is no known exploitation of CVE-2020-25708 in the wild and no public exploit code. ## Other vulnerabilities in Debian Debian Linux - [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild) - [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild) - [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild) - [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild) - [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2020-25708 and fix it if it is affected. What it is: CVE-2020-25708 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 27 Nov 2020. 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-2020-25708 in the wild and no public exploit code. Affected product: Debian Debian Linux. 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-2020-25708/ (Markdown: https://insights.sbomify.com/CVE-2020-25708/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2020-25708 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-25708 - OSV: https://osv.dev/vulnerability/CVE-2020-25708 --- From sbomify Insights: https://insights.sbomify.com/CVE-2020-25708/ Summaries are generated and may contain mistakes; the official description above is the record.