Summary
crossbeam-channel Undefined Behavior before v0.4.4
References
See https://github.com/crossbeam-rs/crossbeam/pull/533, https://github.com/crossbeam-rs/crossbeam/issues/539, and https://github.com/RustSec/advisory-db/pull/425 for more details.
License
This advisory is in the public domain.
Impact
The affected version of this crate's the bounded channel incorrectly assumes that Vec::from_iter has allocated capacity that same as the number of iterator elements. Vec::from_iter does not actually guarantee that and may allocate extra memory. The destructor of the bounded channel reconstructs Vec from the raw pointer based on the incorrect assumes described above. This is unsound and causing deallocation with the incorrect capacity when Vec::from_iter has allocated different sizes with the number of iterator elements.
CVE-2020-15254 has a CVSS score of 8.1 (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 (0.4.4); 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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This has been fixed in crossbeam-channel 0.4.4.
We recommend users to upgrade to 0.4.4.
Frequently Asked Questions
- What is CVE-2020-15254? CVE-2020-15254 is a high-severity security vulnerability in crossbeam-channel (rust), affecting versions = 0.4.3. It is fixed in 0.4.4.
- How severe is CVE-2020-15254? CVE-2020-15254 has a CVSS score of 8.1 (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 crossbeam-channel are affected by CVE-2020-15254? crossbeam-channel (rust) versions = 0.4.3 is affected.
- Is there a fix for CVE-2020-15254? Yes. CVE-2020-15254 is fixed in 0.4.4. Upgrade to this version or later.
- Is CVE-2020-15254 exploitable, and should I be worried? Whether CVE-2020-15254 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-2020-15254 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-2020-15254? Upgrade
crossbeam-channelto 0.4.4 or later.