VulnerabilityAnalyzed

CVE-2026-23519

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.

HIGH 8.9EPSS 0.57%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.57%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

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 4.0: 8.9 HIGHCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.57% probability · 45th percentile
CISA KEV: Not listed
Weakness: CWE-208, CWE-203
Affected: rustcrypto/cmov
Source: security-advisories@github.com

References

https://github.com/RustCrypto/utils/commit/55977257e7c82a309d5e8abfdd380a774f0f9778Patch
https://github.com/RustCrypto/utils/security/advisories/GHSA-2gqc-6j2q-83qpExploit, Vendor Advisory
https://github.com/RustCrypto/utils/security/advisories/GHSA-2gqc-6j2q-83qpExploit, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.