CVE-2020-36436 is a high-severity (CVSS 8.1) CWE-362 vulnerability in unicycle. A fix is available for unicycle — see the affected versions and patch details below.
Data races in unicycle
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2020-36436 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
unicycleReal-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
Affected versions of this crate unconditionally implemented Send & Sync for types PinSlab<T> & Unordered<T, S>. This allows sending non-Send types to other threads and concurrently accessing non-Sync types from multiple threads.
This can result in a data race & memory corruption when types that provide internal mutability without synchronization are contained within PinSlab<T> or Unordered<T, S> and accessed concurrently from multiple threads.
The flaw was corrected in commits 92f40b4 & 6a6c367 by adding trait bound T: Send to Send impls for PinSlab<T> & Unordered<T, S> and adding T: Sync to Sync impls for PinSlab<T> & Unordered<T, S>.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | unicycle | all versions | 0.7.1cargo update -p unicycle --precise 0.7.1 |
Affected Products
unicycleunicycle_projectDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for unicycle, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update unicycle to 0.7.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-36436 is resolved across your whole dependency graph.
Workarounds
Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.
Frequently Asked Questions
Is CVE-2020-36436 in your dependencies?
Find it across crates.io, including transitive dependencies.