Security readout for executives and security teams
Plain-English summary
CVE-2026-4712 is a high-severity Mozilla information disclosure flaw in the Widget: Cocoa component. Mozilla says it is fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9. The main business risk is unintended exposure of sensitive information from users running older versions.
Executive priority
Treat this as a timely browser and mail-client update priority. It affects confidentiality and requires no privileges or user interaction per CVSS. Patch through normal urgent endpoint update processes, especially for users handling sensitive information.
Technical view
The CVE is classified as CWE-200 information disclosure with CVSS 3.1 score 7.5. The vector indicates network attackability, low complexity, no privileges, no user interaction, unchanged scope, and high confidentiality impact. Provided sources do not describe the exact leaked data or root cause details.
Likely exposure
Organizations using Mozilla Firefox, Firefox ESR, Thunderbird, or Thunderbird ESR before the fixed releases should assess exposure. The Cocoa component name may indicate platform-specific relevance, but the provided sources do not explicitly define operating-system scope.
Exploitation context
No active exploitation is stated in the provided sources, and the CVE is not marked in CISA KEV. The CVSS vector indicates the issue could be remotely reachable without authentication or user interaction, but public exploit details are not provided in the source bundle.
Researcher notes
Evidence is limited to Mozilla/CVE metadata. The sources identify the component, impact class, CVSS vector, and fixed versions, but do not provide technical internals, affected OS scope, proof-of-concept status, or data exposure specifics.
Mitigation direction
- Upgrade Firefox to 149 or later where applicable.
- Upgrade Firefox ESR to 140.9 or later.
- Upgrade Thunderbird to 149 or later where applicable.
- Upgrade Thunderbird ESR to 140.9 or later.
- Review Mozilla advisories for product-specific deployment guidance.
Validation and detection
- Inventory Firefox and Thunderbird versions across managed endpoints.
- Confirm ESR channels are at 140.9 or later.
- Confirm rapid-release channels are at 149 or later.
- Check vulnerability scanners for CVE-2026-4712 coverage.
- Monitor Mozilla advisories for additional clarification.
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
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-200: Information exposure and cloud metadata lookup
Information exposure and SSRF weaknesses can make discovery, cloud metadata, and credential material review relevant. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-4712 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
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:N/A:N3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://bugzilla.mozilla.org/show_bug.cgi?id=2017666CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-20/CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-22/CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-23/CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-24/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.
Exposure of Sensitive Information to an Unauthorized Actor
Exposure of Sensitive Information to an Unauthorized Actor represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.