# CVE-2020-8165: ActiveSupport potentially unintended unmarshalling of user-provided objects in MemCacheStore and RedisCacheStore > Attackers can achieve remote code execution by exploiting unsafe deserialization in Rails cache stores when using MemCache or Redis. - **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:** 19 Jun 2020 - **Updated:** 9 May 2025 - **Also known as:** DEBIAN-CVE-2020-8165, GHSA-2p68-f74v-9wc6, SUSE-SU-2020:2899-1, SUSE-SU-2020:2929-1, UBUNTU-CVE-2020-8165, openSUSE-SU-2020:1677-1, openSUSE-SU-2020:1679-1 ## What is CVE-2020-8165? CVE-2020-8165 is a critical unsafe deserialization vulnerability in Debian Debian Linux, published on 19 Jun 2020. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description A deserialization of untrusted data vulnernerability exists in rails < 5.2.4.3, rails < 6.0.3.1 that can allow an attacker to unmarshal user-provided objects in MemCacheStore and RedisCacheStore potentially resulting in an RCE. Weakness: CWE-502 (Deserialization of Untrusted Data) ## Which versions are affected by CVE-2020-8165? 4 open source packages ship an affected version, including activesupport. It affects 3 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `activesupport` | RubyGems | From 5.0.0 | 5.2.4.3 | | `activesupport` | RubyGems | From 5.0.0 | 5.2.4.3 | | `activesupport` | RubyGems | From 6.0.0 | 6.0.3.1 | | `activesupport` | RubyGems | From 6.0.0 | 6.0.3.1 | | `rubygem-activesupport-5_1` | SUSE:Linux Enterprise High Availability Extension 15 | All versions | 5.1.4-3.3.1 | | `rubygem-activesupport-5_1` | SUSE:Linux Enterprise High Availability Extension 15 SP1 | All versions | 5.1.4-3.3.1 | | `rubygem-activesupport-5_1` | SUSE:Linux Enterprise High Availability Extension 15 SP2 | All versions | 5.1.4-3.3.1 | | `rubygem-activesupport-4_2` | SUSE:OpenStack Cloud 7 | All versions | 4.2.9-7.9.1 | | `rubygem-activesupport-4_2` | SUSE:OpenStack Cloud Crowbar 8 | All versions | 4.2.9-7.9.1 | | `rubygem-activesupport-4_2` | SUSE:OpenStack Cloud Crowbar 9 | All versions | 4.2.9-7.9.1 | | `rubygem-activesupport-5_1` | openSUSE:Leap 15.1 | All versions | 5.1.4-lp151.3.3.1 | | `rubygem-activesupport-5_1` | openSUSE:Leap 15.2 | All versions | 5.1.4-lp152.4.3.1 | Products: Debian Debian Linux, Opensuse Leap, Rubyonrails Rails. ## How do I fix CVE-2020-8165? Upgrade activesupport to a fixed version for your release line: 5.2.4.3 or 6.0.3.1. ## Is CVE-2020-8165 being exploited? There is no known exploitation of CVE-2020-8165 in the wild and no public exploit code. Public exploit code: - https://github.com/masahiro331/CVE-2020-8165 (github_poc): https://github.com/masahiro331/CVE-2020-8165 - https://github.com/hybryx/CVE-2020-8165 (github_poc): https://github.com/hybryx/CVE-2020-8165 - https://github.com/umiterkol/CVE-2020-8165--Auto-Shell (github_poc): https://github.com/umiterkol/CVE-2020-8165--Auto-Shell - https://github.com/danielklim/cve-2020-8165-demo (github_poc): https://github.com/danielklim/cve-2020-8165-demo - https://github.com/taipansec/CVE-2020-8165 (github_poc): https://github.com/taipansec/CVE-2020-8165 - https://github.com/AssassinUKG/CVE-2020-8165 (github_poc): https://github.com/AssassinUKG/CVE-2020-8165 ## 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-2020-8165 and fix it if it is affected. What it is: CVE-2020-8165 is a critical unsafe deserialization vulnerability in Debian Debian Linux, published on 19 Jun 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-2020-8165 in the wild and no public exploit code. Affected packages and fixed versions: - activesupport (RubyGems): affected from 5.0.0; fixed in 5.2.4.3 - activesupport (RubyGems): affected from 5.0.0; fixed in 5.2.4.3 - activesupport (RubyGems): affected from 6.0.0; fixed in 6.0.3.1 - activesupport (RubyGems): affected from 6.0.0; fixed in 6.0.3.1 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-2020-8165/ (Markdown: https://insights.sbomify.com/CVE-2020-8165/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2020-8165 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-8165 - OSV: https://osv.dev/vulnerability/CVE-2020-8165 --- From sbomify Insights: https://insights.sbomify.com/CVE-2020-8165/ Summaries are generated and may contain mistakes; the official description above is the record.