Security readout for executives and security teams
Plain-English summary
CVE-2026-2634 affects Firefox for iOS. A malicious script could make attacker-controlled web content appear under a trusted domain in the address bar before the real response arrives. This can support convincing phishing or trust abuse. Mozilla states the issue was fixed in Firefox for iOS 147.4.
Executive priority
Treat as urgent for organizations with managed iOS users relying on Firefox. The vulnerability undermines browser trust signals and can enable convincing deception, but sources do not confirm active exploitation. Update validation should be prioritized over broad incident response unless new evidence emerges.
Technical view
The issue is a CWE-451 user-interface misrepresentation flaw in Firefox for iOS. Scripted navigation could desynchronize displayed web content from the address bar before a response is received, allowing spoofed domain presentation. The source bundle rates it CVSS 9.8 critical with network attack vector and no privileges required.
Likely exposure
Exposure is limited to Mozilla Firefox for iOS installations that have not received the vendor fix. The provided sources name Firefox for iOS and state the fix is in version 147.4. Other Mozilla products are not identified in the provided sources.
Exploitation context
No active exploitation is stated in the provided sources, and this CVE is not marked KEV in the bundle. The practical risk is user deception: attackers may present malicious content as if it came from a trusted domain, increasing phishing and credential-theft risk.
Researcher notes
Bugzilla and Mozilla advisory are the primary references. Public source detail is limited to address-bar/content desynchronization via scripted navigation before response receipt. Avoid assuming exploit availability, affected versions beyond Firefox for iOS, or fixes beyond Mozilla’s stated 147.4 release.
Mitigation direction
- Update Firefox for iOS to version 147.4 if not already installed.
- Check Mozilla’s advisory for any revised version or platform guidance.
- Prioritize managed mobile devices and users handling sensitive accounts.
- Reinforce phishing awareness for mobile browser address-bar spoofing scenarios.
Validation and detection
- Inventory Firefox for iOS versions across managed iOS devices.
- Confirm installed versions are 147.4 or vendor-confirmed fixed releases.
- Review mobile device management compliance reports for outdated Firefox installations.
- Monitor Mozilla advisory and Bugzilla reference for new technical details.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
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ATT&CK lookup starting points
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CWE-451: Exact CWE lookup
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Open ATT&CK lookupCVE-2026-2634 mapping review
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Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://bugzilla.mozilla.org/show_bug.cgi?id=1975529CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-12/CVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
User Interface (UI) Misrepresentation of Critical Information
User Interface (UI) Misrepresentation of Critical Information represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.