Repeated external URL scheme launches could potentially cause a denial of service in Firefox for iOS

{
  "id": "6974c01e721c1e48e66d354ddb17dd60fd13026607f4e537a961d7b0190616c9",
  "url": "https://osv.dev/vulnerability/CVE-2026-86853",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Repeated external URL scheme launches could potentially cause a denial of service in Firefox for iOS",
    "summary": "A malicious webpage could repeatedly trigger external URL schemes, causing system prompts or external application launches. This could make Firefox for iOS temporarily unusable until the page is closed. This vulnerability was fixed in Firefox for iOS 155.1.",
    "evidence": "osv:CVE-2026-86853",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-86853",
      "aliases": [
        "CVE-2026-86853"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/mozilla-mobile/firefox-ios",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "04df3bd66b34441c6b97ee3958535c5bf4633ca4"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:mozilla:firefox_mobile:*:*:*:*:*:iphone_os:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "155.1"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "focus/klar-v155.0",
            "firefox-v155.0",
            "firefox-v154.1",
            "firefox-v153.3",
            "firefox-v153.0",
            "firefox-v152.1",
            "firefox-v151.1",
            "firefox-v151.0",
            "firefox-v150.1",
            "firefox-v149.2",
            "firefox-v149.0",
            "focus/klar-v148.2",
            "firefox-v148.1",
            "firefox-v147.5",
            "firefox-v147.4",
            "firefox-v146.1",
            "firefox-v145.2",
            "firefox-v144.3",
            "firefox-v144.2",
            "firefox-v144.1",
            "focus/klar-v143.0",
            "firefox-v142.0",
            "20.1",
            "AuroraV15",
            "AuroraV14",
            "AuroraV13",
            "AuroraV11",
            "AuroraV10",
            "AuroraV8",
            "AuroraV7",
            "AuroraV6",
            "AuroraV2",
            "AuroraV1",
            "AuroraV3"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-86853.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:50.823841256Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86853.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-86853",
        "https://www.mozilla.org/security/advisories/mfsa2026-89/",
        "https://bugzilla.mozilla.org/show_bug.cgi?id=1847631"
      ],
      "provider_metadata": {
        "cna_assigner": "mozilla",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/86xxx/CVE-2026-86853.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-86853",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 519501,
  "published_at": "2026-09-08T15:14:51.534+00:00"
}