CVE-2026-50185: RustCrypto CMOV provides conditional move CPU intrinsics which are guaranteed on major platforms to execute in

Routine

LOW 3.3UPGRADE

CVE-2026-50185 is a low-severity flaw (CVSS 3.3) affecting cmov. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

RustCrypto CMOV provides conditional move CPU intrinsics which are guaranteed on major platforms to execute in constant-time and not be rewritten as branches by the compiler. From 0.1.1 until 0.5.4, the aarch64 implementations of Cmov and CmovEq in cmov/src/backends/aarch64.rs assume high bits are zero-extended when loading values smaller than a register, so set high bits such as [8..] in a Cmov selector or [16..] of self or other in the u16 and

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	3.3 (Low)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.2% (top 95%)
CISA exploited list	No
Weakness	CWE-758
Published	2026-07-17
Last modified	2026-10-24

Publisher (CNA): GitHub, Inc. · Vendor: rustcrypto

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-17 19:17 UTCPublished CVE record published
2026-10-24 20:10 UTCUpdated Record last modified

rustcrypto cmov UPGRADE

Affected: >= 0.1.1 and < 0.5.4

Fixed in: 0.5.4

Safe to downgrade to: a release before 0.1.1

1. Check installed version

apt-cache policy cmov || rpm -q cmov || cmov --version

2. UPGRADE to 0.5.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade cmov

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade cmov

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 0.1.1 (Debian / Ubuntu)

apt-cache madison cmov sudo apt install cmov=<VERSION_BEFORE_0.1.1> sudo apt-mark hold cmov

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list cmov sudo dnf downgrade cmov-<VERSION_BEFORE_0.1.1> sudo dnf versionlock add cmov

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Advisories and coverage

Official advisories

Amazon Linux 2023 ALAS: ALAS2023-2026-3132 (low): amazon-efs-utils 2026-09-29
Amazon Linux 2 ALAS: ALAS2-2026-3948 (low): amazon-efs-utils 2026-09-28

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-50185?

cmov: upgrade to 0.5.4. Exact commands for each OS are on this page.

Is CVE-2026-50185 being exploited?

CVE-2026-50185 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-50185 affect?

CVE-2026-50185 affects cmov. Severity is low (CVSS 3.3). RustCrypto CMOV provides conditional move CPU intrinsics which are guaranteed on major platforms to execute in constant-time and not be rewritten as branches by the compiler. From 0.1.1 until 0.5.4, the aarch64 implementations of Cmov and C

How urgent is CVE-2026-50185?

Priority 18/100. Public exploit reference

References

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