Vulnerability · Published Jan 15, 2026 · Assigned by GitHub_M
CVE-2026-23519RustCrypto cmov: thumbv6m-none-eabi compiler emits non-constant time assembly when using cmovnz
High 8.9
In plain English
A high-severity security flaw in utils from RustCrypto. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 47% of all known vulnerabilities).
Severity (CVSS 4.0)8.9High
Exploit odds (30 days)0.6%top 53.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| RustCrypto | utils | < 0.4.4 |
Weakness: CWE-208 · 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