CVE-2026-16381
Mozilla Firefox ≤ 140.13.0
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NSummary
CVE-2026-16381 is a critical-severity Origin Validation Error (CWE-346) vulnerability in Mozilla Firefox. Its CVSS base score is 9.1 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Drive-by Compromise (T1189); ranked at the 7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-46218
Vulnerability Data
Same-origin policy bypass in the Networking: DNS component. This vulnerability was fixed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
SOP bypass in browser DNS component directly enables drive-by attacks and client-side exploitation via malicious websites.
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Enforces origin-based information flow rules that directly block the same-origin policy bypass described in this DNS component CVE.
Implements the access decision logic required to uphold same-origin restrictions that the vulnerability circumvents.
Applies boundary protections and DNS traffic controls that can limit exploitation of the origin validation flaw at the network layer.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Authentication directly verifies the source of users/services/hardware, mitigating origin validation failures.
Verifying identity assertions enforces origin validation for conveyed claims.
Documenting authorized flows supports origin validation by defining expected sources.
Protecting networks from unauthorized access requires origin checks on communication sources.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Network security controls enforce origin validation at network boundaries.
Security of network services includes validating the authenticity of service endpoints.
Network segregation reduces exposure but does not directly validate origins.
Application security requirements explicitly call for origin validation of inputs and communications.
Secure architecture principles encourage origin checks but do not mandate them.
Secure coding practices include implementing proper origin validation to prevent spoofing.