GHSA-r8w9-5wcg-vfj7
HIGHMio's tokens for named pipes may be delivered after deregistration
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
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
Impact
When using named pipes on Windows, mio will under some circumstances return invalid tokens that correspond to named pipes that have already been deregistered from the mio registry. The impact of this vulnerability depends on how mio is used. For some applications, invalid tokens may be ignored or cause a warning or a crash. On the other hand, for applications that store pointers in the tokens, this vulnerability may result in a use-after-free.
For users of Tokio, this vulnerability is serious and can result in a use-after-free in Tokio.
The vulnerability is Windows-specific, and can only happen if you are using named pipes. Other IO resources are not affected.
Affected versions
This vulnerability has been fixed in mio v0.8.11.
All versions of mio between v0.7.2 and v0.8.10 are vulnerable.
Tokio is vulnerable when you are using a vulnerable version of mio AND you are using at least Tokio v1.30.0. Versions of Tokio prior to v1.30.0 will ignore invalid tokens, so they are not vulnerable.
Workarounds
Vulnerable libraries that use mio can work around this issue by detecting and ignoring invalid tokens.
Technical details
When an IO resource registered with mio has a readiness event, mio delivers that readiness event to the user using a user-specified token. Mio guarantees that when an IO resource is deregistered, then it will never return the token for that IO resource again. However, for named pipes on windows, mio may sometimes deliver the token for a named pipe even though the named pipe has been previously deregistered.
This vulnerability was originally reported in the Tokio issue tracker: tokio-rs/tokio#6369 This vulnerability was fixed in: tokio-rs/mio#1760 This vulnerability is also known as RUSTSEC-2024-0019.
Thank you to @rofoun and @radekvit for discovering and reporting this issue.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | mio | ≥ 0.7.2&&< 0.8.11 | 0.8.11 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mio. 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 mio to 0.8.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-r8w9-5wcg-vfj7 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-r8w9-5wcg-vfj7 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-r8w9-5wcg-vfj7. 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-r8w9-5wcg-vfj7 in your dependencies?
O3 detects GHSA-r8w9-5wcg-vfj7 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.