RustCrypto Cmov/CmovEq on aarch64 can produce wrong results if high-bits of registers are set

{
  "id": "1d2b9deec761b2adefd00fe610f6bb7ccf9599efd2213a05a895988d5c05fed9",
  "url": "https://osv.dev/vulnerability/CVE-2026-50185",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "RustCrypto Cmov/CmovEq on aarch64 can produce wrong results if high-bits of registers are set",
    "summary": "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. From 0.1.1 until 0.5.4, the aarch64 implementations of Cmov and CmovEq in cmov/src/backends/aarch64.rs assume high bits are zero-extended when loading values smaller than a register, so set high bits such as [8..] in a Cmov selector or [16..] of self or other in the u16 and i16 CmovEq implementations can cause left.cmovz(&right, condition) to produce incorrect output. This issue is fixed in version 0.5.4.",
    "evidence": "osv:CVE-2026-50185",
    "products": [],
    "severity": "low",
    "structured": {
      "id": "CVE-2026-50185",
      "aliases": [
        "CVE-2026-50185",
        "GHSA-3rjw-m598-pq24"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/rustcrypto/utils",
              "type": "GIT",
              "events": [
                {
                  "introduced": "dfb4be5e2a0663e9c72dd1330871557d0bdd6384"
                },
                {
                  "fixed": "5c7e4f9bb31af81bf766360e836b6d633b84dbff"
                },
                {
                  "fixed": "dba6c355c9f241e3726d5ec2a68f9f3b519f6063"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:rustcrypto:cmov:*:*:*:*:*:rust:*:*",
                    "range": [
                      {
                        "introduced": "0.1.1"
                      },
                      {
                        "fixed": "0.5.4"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "dba6c355c9f241e3726d5ec2a68f9f3b519f6063"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "5c7e4f9bb31af81bf766360e836b6d633b84dbff"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "cmov-v0.5.4"
                  }
                ]
              }
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-50185.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:28.211734015Z",
      "provider": "osv",
      "references": [
        "https://github.com/RustCrypto/utils/releases/tag/cmov-v0.5.4",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50185.json",
        "https://github.com/RustCrypto/utils/security/advisories/GHSA-3rjw-m598-pq24",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-50185",
        "https://github.com/RustCrypto/utils/commit/dba6c355c9f241e3726d5ec2a68f9f3b519f6063"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-758"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/50xxx/CVE-2026-50185.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-50185",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 494973,
  "published_at": "2026-07-17T18:35:02.078+00:00"
}