CVE-2020-8927 is a medium-severity (CVSS 6.5) CWE-130 vulnerability in compu-brotli-sys. A fix is available for compu-brotli-sys — see the affected versions and patch details below.
Integer overflow in the bundled Brotli C library
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2020-8927.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2020-8927 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
compu-brotli-sys.NETMicrosoft.NETCore.App.Runtime.linux-arm.NETMicrosoft.NETCore.App.Runtime.linux-arm64.NETMicrosoft.NETCore.App.Runtime.linux-musl-arm64.NETMicrosoft.NETCore.App.Runtime.linux-x64.NETMicrosoft.NETCore.App.Runtime.osx-x64.NETMicrosoft.NETCore.App.Runtime.win-arm.NETMicrosoft.NETCore.App.Runtime.win-arm64+141 moreReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io, NuGet packages — download data is not available via public APIs for these ecosystems.
Description
A buffer overflow exists in the Brotli library versions prior to 1.0.8 where an attacker controlling the input length of a "one-shot" decompression request to a script can trigger a crash, which happens when copying over chunks of data larger than 2 GiB. It is recommended to update your Brotli library to 1.0.8 or later. If one cannot update, we recommend to use the "streaming" API as opposed to the "one-shot" API, and impose chunk size limits.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | compu-brotli-sys | all versions | 1.0.9cargo update -p compu-brotli-sys --precise 1.0.9 |
| .NETNuGet | Microsoft.NETCore.App.Runtime.linux-arm | ≥ 3.0.0&&< 3.1.23 | 3.1.23dotnet add package Microsoft.NETCore.App.Runtime.linux-arm --version 3.1.23 |
| .NETNuGet | Microsoft.NETCore.App.Runtime.linux-arm64 | ≥ 3.0.0&&< 3.1.23 | 3.1.23dotnet add package Microsoft.NETCore.App.Runtime.linux-arm64 --version 3.1.23 |
| .NETNuGet | Microsoft.NETCore.App.Runtime.linux-musl-arm64 | ≥ 3.0.0&&< 3.1.23 | 3.1.23dotnet add package Microsoft.NETCore.App.Runtime.linux-musl-arm64 --version 3.1.23 |
| .NETNuGet | Microsoft.NETCore.App.Runtime.linux-x64 | ≥ 3.0.0&&< 3.1.23 | 3.1.23dotnet add package Microsoft.NETCore.App.Runtime.linux-x64 --version 3.1.23 |
| .NETNuGet | Microsoft.NETCore.App.Runtime.osx-x64 | ≥ 3.0.0&&< 3.1.23 | 3.1.23dotnet add package Microsoft.NETCore.App.Runtime.osx-x64 --version 3.1.23 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for compu-brotli-sys, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update compu-brotli-sys to 1.0.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-8927 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2020-8927 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2020-8927. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| .NET Core on Red Hat Enterprise Linux | rh-dotnet31-dotnet-0:3.1.417-1.el7_9 | RHSA-2022:0829 |
| .NET Core on Red Hat Enterprise Linux | rh-dotnet50-dotnet-0:5.0.212-1.el7_9 | RHSA-2022:0828 |
| Red Hat Enterprise Linux 8 | brotli-0:1.0.6-3.el8 | RHSA-2021:1702 |
| Red Hat Enterprise Linux 8 | dotnet3.1-0:3.1.417-1.el8_5 | RHSA-2022:0827 |
| Red Hat Enterprise Linux 8 | dotnet5.0-0:5.0.212-1.el8_5 | RHSA-2022:0830 |
Frequently Asked Questions
Is CVE-2020-8927 in your dependencies?
O3 Security finds CVE-2020-8927 across crates.io, NuGet, PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.