Security readout for executives and security teams
Plain-English summary
CVE-2026-2803 is a Mozilla Firefox and Thunderbird issue involving information disclosure and bypass of a mitigation in the Settings UI component. Mozilla states it was fixed in Firefox 148 and Thunderbird 148. The main business concern is potential exposure of sensitive information through network-reachable attack surface with no privileges or user interaction required, based on the CVSS vector.
Executive priority
Prioritize routine emergency-style patching for managed browsers and email clients, especially where sensitive data is handled. The issue is high severity, but current public evidence does not show active exploitation. The practical executive action is fast version compliance and exception tracking.
Technical view
The CVE is categorized as CWE-200 and CWE-693: information exposure and protection mechanism failure. CVSS 3.1 is 7.5 high, with AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Source details do not describe the exact data exposed or the bypass mechanics, so technical validation should focus on version inventory and vendor advisories.
Likely exposure
Organizations using Firefox or Thunderbird versions prior to the fixed 148 releases may be exposed. The source bundle does not provide platform-specific scope, configuration prerequisites, or enterprise policy dependencies. Treat managed desktop, VDI, and email-client deployments as the primary inventory targets.
Exploitation context
No public source in the provided bundle states active exploitation, and this CVE is not listed as KEV. The CVSS vector indicates potential remote, low-complexity exploitation without privileges or user interaction, but the available sources do not provide exploit details or proof-of-concept status.
Researcher notes
Available public data is sparse. The CVE names the Settings UI component but does not disclose exact trigger conditions, exposed data, or bypass mechanism. Avoid assuming exploitability beyond the CVSS and Mozilla advisory statements. Validation should remain version- and advisory-driven unless Mozilla publishes more technical detail.
Mitigation direction
- Upgrade Firefox to version 148 or later, following Mozilla guidance.
- Upgrade Thunderbird to version 148 or later, following Mozilla guidance.
- Prioritize systems handling sensitive browsing or email content.
- Confirm enterprise update channels are not pinned below the fixed release.
- Monitor Mozilla advisories for clarifications or follow-up fixes.
Validation and detection
- Inventory Firefox and Thunderbird versions across endpoints.
- Confirm installed versions are 148 or later.
- Review Mozilla MFSA 2026-13 and MFSA 2026-16 for product-specific details.
- Check software deployment tools for failed or deferred updates.
- Document any exceptions where fixed versions cannot be deployed.
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 lookupCWE-693: 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-2026-2803 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=2012012CVE 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.
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.
CWE mapping pending import
This CVE carries a CWE mapping that will resolve to a full Glexia CWE intelligence page after the official CWE import is complete.