Security readout for executives and security teams
Plain-English summary
CVE-2026-4706 is a high-severity Mozilla graphics flaw involving Canvas2D boundary handling. Mozilla says it is fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9. The published CVSS impact is availability-only, meaning disruption or crashes are the stated concern, not data theft.
Executive priority
Treat this as a prompt patching item for Mozilla browser and mail-client fleets. The known impact is service disruption rather than data compromise, but the flaw is high severity and remotely reachable per CVSS. Prioritize standard update deployment and verification.
Technical view
The CVE describes incorrect boundary conditions in Mozilla’s Graphics: Canvas2D component, mapped to CWE-754. CVSS 3.1 is 7.5: network attack vector, low complexity, no privileges, no user interaction, unchanged scope, and high availability impact with no confidentiality or integrity impact stated.
Likely exposure
Organizations using Mozilla Firefox, Firefox ESR, or Thunderbird below the fixed versions named by Mozilla may be exposed. Exposure is most relevant on endpoints and managed desktops where browser or mail-client updates lag. The source bundle does not identify affected operating systems or specific older version ranges.
Exploitation context
No provided source states active exploitation, and the CVE is not marked as CISA KEV in the bundle. The CVSS vector indicates remote, low-complexity exploitation without privileges or user interaction, but the public details provided do not include exploit mechanics or proof-of-concept status.
Researcher notes
Public detail is limited to component, CWE, CVSS, and fixed versions. The Bugzilla and Mozilla advisory links are the key references for deeper triage. Do not infer memory corruption, code execution, or active exploitation from the provided evidence alone.
Mitigation direction
- Upgrade Firefox to Mozilla’s fixed release for your channel.
- Upgrade Firefox ESR to 115.34 or 140.9, as applicable.
- Upgrade Thunderbird to 149 or 140.9, as applicable.
- Review the linked Mozilla advisories for channel-specific guidance.
- Prioritize managed endpoint fleets with delayed browser or mail-client patching.
Validation and detection
- Inventory Firefox, Firefox ESR, and Thunderbird versions across endpoints.
- Compare installed versions to the Mozilla fixed versions named for each channel.
- Confirm enterprise update policies are successfully deploying the fixed releases.
- Check vulnerability scanner findings against Mozilla advisory version data.
- Document exceptions and monitor Mozilla advisories for follow-up guidance.
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-754: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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-2026-4706 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:N/I:N/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:N/I:N/A:H3.93.6Primary 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:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://bugzilla.mozilla.org/show_bug.cgi?id=2015091CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-20/CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-21/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.
Improper Check for Unusual or Exceptional Conditions
Improper Check for Unusual or Exceptional Conditions represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.