ordered_float:NotNan may contain NaN after panic in assignment operators

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.5 · CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2020-35923: 0.39% estimated exploitation activity in the next 30 days; percentile 33.36 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

After using an assignment operators such as NotNan::addassign, NotNan::mulassign, 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.

Published by the source

25 Aug 2021, 20:50 UTC

Last modified by the source

13 Jun 2023, 19:52 UTC

Source last checked

26 Oct 2026, 15:34 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-566x-hhrf-qf8m

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# Patch Next advisory brief: CVE-2020-35923

Advisory: ordered_float:NotNan may contain NaN after panic in assignment operators
IDs: CVE-2020-35923, GHSA-566x-hhrf-qf8m
Record: https://patchnext.com/advisories/cve-2020-35923 (revision 1, source checked 26 Oct 2026, 15:34 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: ordered-float 2.0.1, 1.1.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io ordered-float: affected >= 2.0.0, <= 2.0.0; >= 0.2.2, < 1.1.1; fixed in 2.0.1, 1.1.1

## Suggested inspection (read-only)
- crates.io ordered-float: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on ordered-float.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-566x-hhrf-qf8m (GitHub-reviewed advisory GHSA-566x-hhrf-qf8m lists affected ranges: crates.io ordered-float >=2.0.0 =0.2.2 <1.1.1)

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