Vulnerability-Lookup

CVE-2026-86853 (GCVE-0-2026-86853)

Vulnerability from cvelistv5 – Published: 2026-09-08 15:14 – Updated: 2026-09-08 15:48

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.

Severity

4.3 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-08 15:47 UTC

CWE

CWE-451 - User Interface (UI) Misrepresentation of Critical Information

Assigner

mozilla mitre root

References

2 references

URL	Tags
https://bugzilla.mozilla.org/show_bug.cgi?id=1847631
https://www.mozilla.org/security/advisories/mfsa2…

Impacted products

1 product

Vendor	Product	Version	CPE status
Mozilla	Firefox for iOS	Unaffected: 155.1 , ≤ * (rpm)	guessed

Credits

Amit Gajbhare

Show details on NVD website

JSON

To clipboard

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              "attackVector": "NETWORK",
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              "confidentialityImpact": "NONE",
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              "userInteraction": "REQUIRED",
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            }
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      "title": "Repeated external URL scheme launches could potentially cause a denial of service in Firefox for iOS"
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CERTFR-2026-AVI-1142

Vulnerability from certfr_avis - Published: 2026-09-09 - Updated: 2026-09-09

Une vulnérabilité a été découverte dans Mozilla Firefox. Elle permet à un attaquant de provoquer un déni de service à distance.

Solutions

Se référer au bulletin de sécurité de l'éditeur pour l'obtention des correctifs (cf. section Documentation).

Impacted products

	Vendor	Product	Description
	Mozilla	Firefox	Firefox pour iOS versions antérieures à 155.1

References

Title

Publication Time

FKIE_CVE-2026-86853

Vulnerability from fkie_nvd - Published: 2026-09-08 16:18 - Updated: 2026-09-08 19:07

Severity

4.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

Summary

References

	URL	Tags
	security@mozilla.org	https://bugzilla.mozilla.org/show_bug.cgi?id=1847631
	security@mozilla.org	https://www.mozilla.org/security/advisories/mfsa2026-89/

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "Firefox for iOS",
          "vendor": "Mozilla",
          "versions": [
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "155.1",
              "versionType": "rpm"
            }
          ]
        }
      ],
      "source": "security@mozilla.org"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    }
  ],
  "id": "CVE-2026-86853",
  "lastModified": "2026-09-08T19:07:12.210",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 4.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 1.4,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
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        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
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          "options": [
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      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1847631"
    },
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      "source": "security@mozilla.org",
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-89/"
    }
  ],
  "sourceIdentifier": "security@mozilla.org",
  "vulnStatus": "Awaiting Analysis",
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          "value": "CWE-451"
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      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary"
    }
  ]
}

GHSA-4C3M-8R8C-3RF3

Vulnerability from github – Published: 2026-09-08 18:31 – Updated: 2026-09-08 18:31

Details

Severity

4.3 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2026-86853"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-451"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-08T16:18:37Z",
    "severity": "MODERATE"
  },
  "details": "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.",
  "id": "GHSA-4c3m-8r8c-3rf3",
  "modified": "2026-09-08T18:31:54Z",
  "published": "2026-09-08T18:31:54Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-86853"
    },
    {
      "type": "WEB",
      "url": "https://bugzilla.mozilla.org/show_bug.cgi?id=1847631"
    },
    {
      "type": "WEB",
      "url": "https://www.mozilla.org/security/advisories/mfsa2026-89"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

CVE-2026-86853 (GCVE-0-2026-86853)

CERTFR-2026-AVI-1142

Solutions

FKIE_CVE-2026-86853

GHSA-4C3M-8R8C-3RF3

Tags

Sightings

Nomenclature