Security advisory

{
  "id": "3aa3fa5594f546d4b3b1e28535ad64cdf28da11813b387c63b4ffbecb9f9f493",
  "url": "https://osv.dev/vulnerability/CVE-2021-43844",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-43844",
    "summary": "MSEdgeRedirect is a tool to redirect news, search, widgets, weather, and more to a user's default browser. MSEdgeRedirect versions before 0.5.0.1 are vulnerable to Remote Code Execution via specifically crafted URLs. This vulnerability requires user interaction and the acceptance of a prompt. With how MSEdgeRedirect is coded, parameters are impossible to pass to any launched file. However, there are two possible scenarios in which an attacker can do more than a minor annoyance. In Scenario 1 (confirmed), a user visits an attacker controlled webpage; the user is prompted with, and downloads, an executable payload; the user is prompted with, and accepts, the aforementioned crafted URL prompt; and RCE executes the payload the user previously downloaded, if the download path is successfully guessed. In Scenario 2 (not yet confirmed), a user visits an attacked controlled webpage; the user is prompted with, and accepts, the aforementioned crafted URL prompt; and a payload on a remote, attacker controlled, SMB server is executed. The issue was found in the _DecodeAndRun() function, in which I incorrectly assumed _WinAPI_UrlIs() would only accept web resources. Unfortunately, file:/// passes the default _WinAPI_UrlIs check(). File paths are now directly checked for and must fail. There is no currently known exploitation of this vulnerability in the wild. A patched version, 0.5.0.1, has been released that checks for and denies these crafted URLs. There are no workarounds for this issu",
    "evidence": "osv:CVE-2021-43844",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2021-43844",
      "aliases": [
        "CVE-2021-43844",
        "GHSA-95v4-748v-fmf9"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/rcmaehl/msedgeredirect",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "13edaeb95c3f375c9425fc2c04aed90b47633996"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:msedgeredirect_project:msedgeredirect:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.5.0.1"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "13edaeb95c3f375c9425fc2c04aed90b47633996"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "0.5.0.1"
                  }
                ]
              }
            }
          ],
          "versions": [
            "0.5.0.0",
            "0.4.1.0",
            "0.4.0.0",
            "0.3.0.0",
            "0.2.0.0",
            "0.1.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-43844.json"
          }
        }
      ],
      "modified": "2026-10-20T10:55:04.979095415Z",
      "provider": "osv",
      "references": [
        "https://github.com/rcmaehl/MSEdgeRedirect/releases/tag/0.5.0.1",
        "https://github.com/rcmaehl/MSEdgeRedirect/security/advisories/GHSA-95v4-748v-fmf9"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-43844",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 386848,
  "published_at": "2021-12-20T22:15:07.883+00:00"
}