Security readout for executives and security teams
Plain-English summary
CVE-2026-2804 is a Mozilla browser and email client memory-safety flaw in JavaScript WebAssembly handling. A user would need to interact with malicious content, such as a crafted web page or message. Mozilla says it was fixed in Firefox 148 and Thunderbird 148. No provided source indicates active exploitation.
Executive priority
Treat this as a routine but timely endpoint patching priority. It is not flagged as actively exploited, but browsers and email clients are common attack entry points. Ensure Mozilla updates are completed in the normal security patch window, with priority for internet-facing and high-risk user groups.
Technical view
The issue is a use-after-free (CWE-416) in the JavaScript: WebAssembly component. CVSS 3.1 is 5.4: network-reachable, low complexity, no privileges required, but user interaction required; confidentiality and integrity impact are low, with no availability impact stated. Mozilla lists fixes in Firefox 148 and Thunderbird 148.
Likely exposure
Organizations using Mozilla Firefox or Thunderbird versions not updated to the fixed 148 release may be exposed. Exposure is highest where users browse untrusted sites, open links, or process untrusted email content. The source bundle does not provide specific vulnerable version ranges beyond the fixed releases.
Exploitation context
The CVSS vector indicates remote exploitation is possible with user interaction. The flaw is in WebAssembly-related JavaScript memory handling, which is typically reachable through web content. KEV is false, and the provided sources do not report exploitation in the wild or public exploit availability.
Researcher notes
Public details are limited in the supplied sources. The Bugzilla issue is referenced, but the bundle does not include exploit details or a full vulnerable-version range. Avoid assuming broader product impact. Validate against Mozilla advisories MFSA 2026-13 and MFSA 2026-16 and the CVE record.
Mitigation direction
- Update Firefox to version 148 or later, following Mozilla advisory MFSA 2026-13.
- Update Thunderbird to version 148 or later, following Mozilla advisory MFSA 2026-16.
- Prioritize updates for users who browse untrusted sites or handle external email.
- If 148 is unavailable in your channel, check Mozilla vendor guidance.
Validation and detection
- Inventory deployed Firefox and Thunderbird versions across managed endpoints.
- Confirm Firefox is at version 148 or later.
- Confirm Thunderbird is at version 148 or later.
- Review patch management records for Mozilla advisory coverage.
- Monitor Mozilla advisories and CVE records for 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-2026-2804 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
- Medium
- CVSS
- 5.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/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:R/S:U/C:L/I:L/A:N2.82.5Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.4MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://bugzilla.mozilla.org/show_bug.cgi?id=2013584CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-13/CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-16/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.