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Full vulnerability report · 2026
CVE-2026-81267High confidence

Stalled popup navigation could allow address bar origin spoofing in Firefox for iOS

Mozilla · Firefox for iOS

5.4MediumCVSS 3.1
Recommended action
Scheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:Medium, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 0.26% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs Mozilla Firefox for iOS and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: As exposure requiresRemediation target: Within 365 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-68739

No EUVD known-exploited evidence

A malicious webpage could stall a popup's cross-origin navigation after commit, causing the address bar to display the destination origin while continuing to render attacker-controlled content. This vulnerability was fixed in Firefox for iOS 155.0.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
5.4 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
01

What, why and how

A malicious webpage could stall a popup's cross-origin navigation after commit, causing the address bar to display the destination origin while continuing to render attacker-controlled content. This vulnerability was fixed in Firefox for iOS 155.0.

What

A malicious webpage could stall a popup's cross-origin navigation after commit, causing the address bar to display the destination origin while continuing to render attacker-controlled content. This vulnerability was fixed in Firefox for iOS 155.0.

Why

The user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

A malicious webpage could stall a popup's cross-origin navigation after commit, causing the address bar to display the destination origin while continuing to render attacker-controlled content. This vulnerability was fixed in Firefox for iOS 155.0.

Why

The user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → User Interface (UI) Misrepresentation of Critical Information → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
Required interaction required
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-451 ↗

CWE-451: User Interface (UI) Misrepresentation of Critical Information. The user interface (UI) does not properly represent critical information to the user, allowing the information - or its source - to be obscured or spoofed. This is often a component in phishing attacks.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SUnchangedScope: The security impact remains within the vulnerable component's authority.CLowConfidentiality impact: A successful attack can cause a limited loss.INoneIntegrity impact: No direct loss is represented by this metric.ALowAvailability impact: A successful attack can cause a limited loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-451
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-68739Official EUVD mapping

A malicious webpage could stall a popup's cross-origin navigation after commit, causing the address bar to display the destination origin while continuing to render attacker-controlled content. This vulnerability was fixed in Firefox for iOS 155.0.

Official EUVD record ↗
BSI · German · WID-SEC-2026-3103Mozilla Firefox: Schwachstelle ermöglicht Darstellen falscher Informationen

Ein entfernter, anonymer Angreifer kann eine Schwachstelle in Mozilla Firefox ausnutzen, um falsche Informationen darzustellen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260902Security Bulletin 2 Sept 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 2 Sept 2026, published on 2 September 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1099Vulnérabilité dans Mozilla Firefox pour iOS

Une vulnérabilité a été découverte dans Mozilla Firefox pour iOS. Elle permet à un attaquant de provoquer un contournement de la politique de sécurité.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-031916Mozilla FoundationのMozilla Firefox Mobileにおけるユーザインターフェースにおける重要情報の誤った表示に関する脆弱性

悪意のあるウェブページは、ポップアップのコミット後のクロスオリジンナビゲーションを停止させることができ、アドレスバーには目的のオリジンが表示されたまま攻撃者が制御するコンテンツをレンダリングし続ける可能性があります。この脆弱性は、Firefox for iOS 155.0で修正されました。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
See the vendor and CVE records for the affected range.
Fixed
Firefox for iOS: 155.0 ≤ *
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
Official vendor articles2 stored documents

Linked articles are downloaded and versioned as source evidence. A CVE mention or approved update relationship does not, by itself, verify a fix for every product branch.

04

Evidence and provenance

Published 31 Aug 2026 · Last source change 31 Aug 2026, 20:09 UTC · CWE-451 · User Interface (UI) Misrepresentation of Critical Information

CVE recordCVE.org · 5.2
CVSS sourceCISA ADP
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-09-01
European sourceENISA EUVD · EUVD-2026-68739
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCISA ADP
NVD statusNVD enriched

Missing structured fields: affected versions. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates ↗
  1. ENISA EUVD mappingEUVD-2026-68739 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-68739"}
    ENISA EUVD ↗
  2. Vendor guidanceAuthoritative vendor guidance changed: added vendor advisory: mozilla.org/mfsa2026-81.
    Before
    remediation: bugzilla.mozilla.org/show_bug.cgi?id=2052758
    After
    remediation: bugzilla.mozilla.org/show_bug.cgi?id=2052758 · vendor advisory: mozilla.org/mfsa2026-81
    security@mozilla.org ↗
  3. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-68739↗Vendor advisory↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-81267 · cve.blacktree.nl