CVE-2020-8927
MEDIUMInteger overflow in the bundled Brotli C library
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.
Blast Radius
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 | 1.0.9 |
| .NETNuGet | Microsoft.NETCore.App.Runtime.linux-arm | ≥ 3.0.0&&< 3.1.23 | 3.1.23 |
| .NETNuGet | Microsoft.NETCore.App.Runtime.linux-arm64 | ≥ 3.0.0&&< 3.1.23 | 3.1.23 |
| .NETNuGet | Microsoft.NETCore.App.Runtime.linux-musl-arm64 | ≥ 3.0.0&&< 3.1.23 | 3.1.23 |
| .NETNuGet | Microsoft.NETCore.App.Runtime.linux-x64 | ≥ 3.0.0&&< 3.1.23 | 3.1.23 |
| .NETNuGet | Microsoft.NETCore.App.Runtime.osx-x64 | ≥ 3.0.0&&< 3.1.23 | 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. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
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 pinpoints whether CVE-2020-8927 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
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.
Frequently Asked Questions
Is CVE-2020-8927 in your dependencies?
O3 detects CVE-2020-8927 across crates.io, NuGet, PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.