Security readout for executives and security teams
Plain-English summary
Mozilla describes CVE-2026-2800 as a critical spoofing flaw in the WebAuthn component in Firefox for Android. WebAuthn is used for passkey and security-key authentication, so spoofing risk can affect trust in sign-in flows. Mozilla says the issue was fixed in Firefox 148 and Thunderbird 148.
Executive priority
Prioritize remediation for managed Android users and environments relying on WebAuthn or passkeys. The issue is rated critical, but public evidence provided here does not confirm active exploitation.
Technical view
The CVE is categorized as CWE-290, with CVSS 3.1 score 9.8 and vector AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. The public summary identifies a spoofing issue in Firefox for Android’s WebAuthn component. The bundle also lists Thunderbird 148 as fixed, but the Android-specific impact details are limited.
Likely exposure
Primary exposure is organizations with Firefox for Android installations not updated to Mozilla’s fixed release. Thunderbird is also named as fixed in 148, so vulnerability managers should verify whether deployed Thunderbird versions are in scope using Mozilla advisories.
Exploitation context
The provided sources do not show CISA KEV listing or public active exploitation. Treat this as urgent because of Mozilla’s critical severity and CVSS 9.8 rating, not because exploitation is confirmed.
Researcher notes
Public detail is sparse. Bugzilla and Mozilla advisories are the key sources for deeper triage. Avoid assuming exploitability beyond the CVSS vector and Mozilla description. The affected-versus-fixed version wording in the bundle should be verified against Mozilla’s advisory text.
Mitigation direction
- Update Firefox for Android to Mozilla’s fixed version 148 or later.
- Update Thunderbird to version 148 or later where deployed.
- Review Mozilla advisories MFSA 2026-13 and MFSA 2026-16 for product-specific guidance.
- If update status is unclear, follow current Mozilla vendor guidance.
Validation and detection
- Inventory Firefox for Android installations across managed mobile devices.
- Confirm Firefox for Android is updated to version 148 or later.
- Inventory Thunderbird installations and confirm version 148 or later.
- Check Mozilla advisories for any revised affected-version details.
- Monitor CVE and Mozilla pages for updated exploit or mitigation information.
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-290: 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-2026-2800 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
- 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=1988145CVE 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.
Authentication Bypass by Spoofing
Authentication Bypass by Spoofing represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.