CVE-2026-23519 HIGH

CVE-2026-23519: RustCrypto cmov: thumbv6m-none-eabi compiler emits non-constant time assembly when using cmovnz

Vendor Rustcrypto
Product utils
Weakness CWE-208
Published January 15, 2026
Last update January 15, 2026
View on NVD All CVEs

CVSS base score

8.9/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Confidentiality —
Integrity —

CVSS vector

CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

January 15, 2026 CVE published
January 15, 2026 Record updated