Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:HSummary
CVE-2026-7321 is a critical-severity Classic Buffer Overflow (CWE-120) vulnerability in Mozilla Firefox. Its CVSS base score is 9.6 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 18th 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 SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-7321 is a sandbox escape vulnerability stemming from incorrect boundary conditions, classified under CWE-120 (Buffer Copy without Bounds Check), in the WebRTC Networking component. It affects Mozilla Firefox, Thunderbird, Firefox ESR, and Thunderbird ESR prior to their respective fixed versions: Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, and Thunderbird ESR 140.10.1. The vulnerability carries a CVSS v3.1 base score of 9.6, reflecting its critical severity due to network accessibility, low attack complexity, and high potential impact.
An attacker can exploit this vulnerability remotely over the network without privileges by tricking a user into interacting with malicious content, such as visiting a specially crafted webpage that triggers the WebRTC Networking flaw. Successful exploitation changes the scope from the sandboxed context to the broader system, granting high confidentiality, integrity, and availability impacts, potentially allowing arbitrary code execution, data theft, or full system compromise on the targeted machine.
Mozilla's security advisories (MFSA 2026-30, 2026-33, 2026-36, and 2026-39) and the associated Bugzilla entry (bug 2029461) confirm the issue was addressed in the specified versions. Security practitioners should prioritize updating affected browsers and email clients to the patched releases, disable WebRTC if not required, and educate users on avoiding suspicious links or media streams.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-26058
Vulnerability Data
Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking component. This vulnerability was fixed in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, and Thunderbird 140.10.1.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V5.2.1
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and analysis can find missing size checks before deployment.
Input validation directly enforces size checks before buffer copies.
Engineering principles require bounds checking and safe buffer handling in design.
Memory protection limits the impact of an overflow once it occurs.
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.
Secure development practices directly enforce bounds checking and input validation that prevent classic buffer overflows.
Vulnerability identification processes such as code review or scanning detect classic buffer overflows before exploitation.
Routine patching replaces vulnerable code containing unchecked buffer copies with corrected versions.
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.
Secure coding directly requires bounds-checked memory operations, addressing the root cause of CWE-120.
Security testing in development and acceptance can detect buffer overflows through fuzzing and static analysis, though it does not prevent them at the source.
Secure development life cycle mandates processes that can include input validation and bounds checking to prevent buffer overflows.
Application security requirements can specify input-size validation and safe buffer handling to mitigate classic buffer overflows.
Secure system architecture and engineering principles promote defensive coding patterns that reduce the likelihood of unchecked buffer copies.