Security readout for executives and security teams
Plain-English summary
CVE-2026-2787 is a high-severity Mozilla browser and mail-client memory safety issue. A user may need to visit or open attacker-controlled content for exploitation. Successful exploitation could compromise confidentiality, integrity, and availability. Mozilla states it is fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Executive priority
Treat as a prompt patching item for browsers and email clients. The impact rating is high, but current provided evidence does not show known active exploitation. Focus on rapid update coverage across user endpoints.
Technical view
The issue is a use-after-free vulnerability in the DOM Window and Location component, classified as CWE-416. The CVSS 3.1 score is 8.8 with network attack vector, low complexity, no privileges required, and user interaction required. Vendor advisories identify fixed Mozilla Firefox, Firefox ESR, and Thunderbird releases.
Likely exposure
Organizations using Firefox, Firefox ESR, or Thunderbird below the fixed releases may be exposed. Risk is higher where users browse untrusted websites, open external links, or process email content in Thunderbird.
Exploitation context
The provided sources do not indicate active exploitation, and the CVE is not listed as KEV in the bundle. The CVSS vector indicates exploitation is network-based, low complexity, requires no attacker privileges, and requires user interaction.
Researcher notes
Do not assume exploit availability from the CVE alone. Review Mozilla advisories and Bugzilla entry for component details, affected branches, and any later clarifications. The public bundle identifies the bug class and fixed releases, but not a safe workaround beyond updating.
Mitigation direction
- Update Firefox to 148 or the applicable ESR fixed release.
- Update Thunderbird to 148 or 140.8 as applicable.
- Prioritize managed endpoints with external web and email exposure.
- If unable to update, check Mozilla advisories for current vendor guidance.
Validation and detection
- Inventory deployed Firefox, Firefox ESR, and Thunderbird versions.
- Confirm Firefox ESR is at 115.33 or 140.8 where applicable.
- Confirm Firefox standard release is 148 or later.
- Confirm Thunderbird is 148 or 140.8 where applicable.
- Review patch management reports for failed or deferred Mozilla updates.
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-416: 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-2026-2787 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
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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:R/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://bugzilla.mozilla.org/show_bug.cgi?id=2014560CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-13/CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-14/CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-15/CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-16/CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-17/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.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.