Summary
Mio's tokens for named pipes may be delivered after deregistration
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.
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.
Memory is accessed after it has been freed, leading to undefined behavior in native code. Typical impact: memory corruption, crash, or potential code execution.
CVE-2024-27308 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.8.11); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2024-27308? CVE-2024-27308 is a high-severity use after free vulnerability in mio (rust), affecting versions >= 0.7.2, <= 0.8.10. It is fixed in 0.8.11. Memory is accessed after it has been freed, leading to undefined behavior in native code.
- How severe is CVE-2024-27308? CVE-2024-27308 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of mio are affected by CVE-2024-27308? mio (rust) versions >= 0.7.2, <= 0.8.10 is affected.
- Is there a fix for CVE-2024-27308? Yes. CVE-2024-27308 is fixed in 0.8.11. Upgrade to this version or later.
- Is CVE-2024-27308 exploitable, and should I be worried? Whether CVE-2024-27308 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2024-27308 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2024-27308? Upgrade
mioto 0.8.11 or later.