GHSA-9q5j-jm53-v7vr
CRITICALlz4-sys vulnerable to memory corruption via issue in liblz4
Blast Radius
lz4-sysReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
lz4-sys up to v1.9.3 bundles a version of liblz4 that is vulnerable to CVE-2021-3520.
Attackers could craft a payload that triggers an integer overflow upon decompression, causing an out-of-bounds write.
The flaw has been corrected in version v1.9.4 of liblz4, which is included in lz4-sys 1.9.4.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | lz4-sys | all versions | 1.9.4 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for lz4-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 lz4-sys to 1.9.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9q5j-jm53-v7vr 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 GHSA-9q5j-jm53-v7vr 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 GHSA-9q5j-jm53-v7vr. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-9q5j-jm53-v7vr in your dependencies?
O3 detects GHSA-9q5j-jm53-v7vr across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.