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HIGH severity

CVE-2020-36444 — async-coap

HIGH

CVE-2020-36444 is a high-severity (CVSS 8.1) CWE-362 vulnerability in async-coap. No vendor fix is recorded yet; mitigation options are listed below.

Data races in async-coap

Also known asRUSTSEC-2020-0124
Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
None indexed
Exploitation data as of Oct 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.8%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs54th percentile — riskier than 54% of all scored CVEsHighest risk
0.00%0.42%0.84%1.27%0.3%0.8%Apr 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2020-36444 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🦀async-coap

Real-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

An issue was discovered in the async-coap crate through 2020-12-08 for Rust. Affected versions of this crate implement Send/Sync for ArcGuard<RC, T> with no trait bounds on RC. This allows users to send RC: !Send to other threads and also allows users to concurrently access Rc: !Sync from multiple threads.

This can result in memory corruption from data race or other undefined behavior caused by sending T: !Send to other threads (e.g. dropping MutexGuard<T> in another thread that didn't lock its mutex).

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
🦀crates.ioasync-coapall versionsNo fix

Affected Products

1 product · 1 configurations
Application
async-coapasync-coap_project
≤ 2020-12-08
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for async-coap, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Remediation status

    No patched version of async-coap has shipped for CVE-2020-36444 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

  3. Mitigate without a patch

    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

An issue was discovered in the async-coap crate through 2020-12-08 for Rust. Affected versions of this crate implement Send/Sync for `ArcGuard<RC, T>` with no trait bounds on `RC`. This allows users to send `RC: !Send` to other threads and also allows users to concurrently access `Rc: !Sync` from multiple threads. This can result in memory corruption from data race or other undefined behavior caused by sending `T: !Send` to other threads (e.g. dropping `MutexGuard<T>` in another thread that didn't lock its mutex).
O3 Security · Impact-Aware SCA

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CVE-2020-36444: async-coap (High 8.1)