by Kastro
Paper/Archive/CVE-2026-23519

CVE-2026-23519

RustCrypto utils — RustCrypto cmov: thumbv6m-none-eabi compiler emits non-constant time assembly when using cmovnz

EPSS 0.6%public exploitCVSS 9.8
critical.is priorityof 100
49
CVSS 9.8 (NVD)9.8 / 10 × 3029.4Not in CISA KEV+300.0EPSS percentile 46.5.465 × 209.3Exploit: SSVC poc+1010.0SSVC exploitation: poc+100.0
Description · from the CVE record

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

ProductAffectedFixed inSource
utils< 0.4.4–CNA

Scores by source

NVD9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub_M (CNA)8.9CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N
CISA ADPSSVCExploitation: poc · Automatable: no · Technical impact: partial

References

exploitgithub.com/RustCrypto/utils/security/advisories/GHSA-2gqc-6j2q-83qprefgithub.com/RustCrypto/utils/commit/55977257e7c82a309d5e8abfdd380a774f0f9778