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

{
    "lastseen": "",
    "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.",
    "published": "2026-01-15T19:13:54.440Z",
    "modified": "2026-01-15T19:57:48.741Z",
    "type": "cve",
    "title": "RustCrypto cmov: thumbv6m-none-eabi compiler emits non-constant time assembly when using cmovnz",
    "source": "GitHub_M",
    "references": "https://github.com/RustCrypto/utils/security/advisories/GHSA-2gqc-6j2q-83qp\nhttps://github.com/RustCrypto/utils/commit/55977257e7c82a309d5e8abfdd380a774f0f9778",
    "id": "CVE-2026-23519",
    "bulletinFamily": "",
    "cwe": [
        "CWE-208"
    ],
    "cvelist": null,
    "sourceData": "RustCrypto utils < 0.4.4",
    "sourceHref": "",
    "cvss": {
        "score": 8.9,
        "severity": "HIGH",
        "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",
        "version": "4.0"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
            "scope": "",
            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "utils",
    "version": "< 0.4.4",
    "vendor": "RustCrypto",
    "ai_description": "RustCrypto CMOV emits non-constant time assembly when using cmovnz on thumbv6m-none-eabi compiler",
    "ai_severity": "High",
    "ai_vendor": "RustCrypto",
    "ai_product": "RustCrypto utils",
    "ai_version": "< 0.4.4",
    "ai_score": 8.9
}