CVE-2020-35922 is a medium-severity (CVSS 5.5) vulnerability in mio. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for mio — see the affected versions and patch details below.
mio invalidly assumes the memory layout of std::net::SocketAddr
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
mioReal-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
The mio crate has assumed std::net::SocketAddrV4 and std::net::SocketAddrV6 have the same memory layout as the system C representation sockaddr. It has simply casted the pointers to convert the socket addresses to the system representation. The standard library does not say anything about the memory layout, and this will cause invalid memory access if the standard library changes the implementation. No warnings or errors will be emitted once the change happens.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | mio | ≥ 0.7.0&&< 0.7.6 | 0.7.6cargo update -p mio --precise 0.7.6 |
Affected Products
miomio_projectResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mio, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update mio to 0.7.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35922 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.
Frequently Asked Questions
Is CVE-2020-35922 in your dependencies?
Find it across crates.io, including transitive dependencies.