CVE-2020-35923 is a medium-severity (CVSS 5.5) Use After Free vulnerability in ordered-float. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for ordered-float — see the affected versions and patch details below.
ordered_float:NotNan may contain NaN after panic in assignment operators
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
ordered-float🦀ordered-floatReal-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
After using an assignment operators such as NotNan::add_assign, NotNan::mul_assign, etc., it was possible for the resulting NotNan value to contain a NaN. This could cause undefined behavior in safe code, because the safe NotNan::cmp method contains internal unsafe code that assumes the value is never NaN. (It could also cause undefined behavior in third-party unsafe code that makes the same assumption, as well as logic errors in safe code.)
This was mitigated starting in version 0.4.0, by panicking if the assigned value is NaN. However, in affected versions from 0.4.0 onward, code that uses the NotNan value during unwinding, or that continues after catching the panic, could still observe the invalid value and trigger undefined behavior.
The flaw is fully corrected in versions 1.1.1 and 2.0.1, by ensuring that the assignment operators panic without modifying the operand, if the result would be NaN.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | ordered-float | ≥ 2.0.0&&< 2.0.1 | 2.0.1cargo update -p ordered-float --precise 2.0.1 |
| 🦀crates.io | ordered-float | ≥ 0.2.2&&< 1.1.1 | 1.1.1cargo update -p ordered-float --precise 1.1.1 |
Affected Products
ordered-floatordered-float_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 ordered-float, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update ordered-float to 2.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-35923 is resolved across your whole dependency graph.
Workarounds
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.
Frequently Asked Questions
Is CVE-2020-35923 in your dependencies?
Find it across crates.io, including transitive dependencies.