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CVE-2026-23519

Rustcrypto Cmov vulnerability

9.8 CRITICALPublic exploitEPSS 0.57%
  1. Published15 Jan 2026

Description

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. Prior to 0.4.4, the thumbv6m-none-eabi (Cortex M0, M0+ and M1) compiler emits non-constant time assembly when using cmovnz (portable version). This vulnerability is fixed in 0.4.4.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

Rustcrypto Cmov< 0.4.4

Remediation

Fixed in
Rustcrypto Cmov≥ 0.4.4

References

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Frequently asked

Is CVE-2026-23519 being actively exploited?

CVE-2026-23519 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.57%.

How severe is CVE-2026-23519?

CVE-2026-23519 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.57% probability of exploitation.

Which products are affected by CVE-2026-23519?

Affected products include Rustcrypto Cmov.

How do I fix CVE-2026-23519?

Upgrade affected software to a fixed version, for example Rustcrypto Cmov 0.4.4 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.