CVE-2026-2806
Published: 24 February 2026
Summary
CVE-2026-2806 is a critical-severity Use of Uninitialized Resource (CWE-908) 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 19.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-16 (Memory Protection) and SI-2 (Flaw Remediation).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
SI-2 mandates timely flaw remediation, directly requiring patching of Firefox and Thunderbird to version 148 to eliminate the uninitialized memory vulnerability.
SI-16 implements memory protection controls like ASLR and stack canaries that mitigate exploitation of uninitialized memory for information disclosure and denial-of-service.
SI-5 ensures receipt and action on vendor security advisories like MFSA 2026-13, enabling prompt awareness and patching of CVE-2026-2806.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Uninitialized memory use in browser graphics/text enables remote exploitation via malicious web content (drive-by) with no user interaction required, directly supporting T1189; the described high-impact crashes also map to application exploitation for DoS under T1499.004. No RCE or code execution is indicated, limiting additional mappings.
NVD Description
Uninitialized memory in the Graphics: Text component. This vulnerability was fixed in Firefox 148 and Thunderbird 148.
Deeper analysisAI
CVE-2026-2806 is a critical vulnerability involving uninitialized memory in the Graphics: Text component, affecting Mozilla Firefox and Thunderbird. Assigned CWE-908 (Use of Uninitialized Resource) and CWE-457 (Use of Uninitialized Variable), it received a CVSS v3.1 base score of 9.1, reflecting its high severity due to network accessibility, low attack complexity, and no requirements for privileges or user interaction.
A remote, unauthenticated attacker can exploit this vulnerability over the network with low complexity and no user interaction. Successful exploitation enables high-impact confidentiality violations, such as disclosure of sensitive information from uninitialized memory, alongside high-impact availability disruptions, potentially leading to denial-of-service conditions like application crashes.
Mozilla addressed the issue in Firefox version 148 and Thunderbird version 148, as detailed in security advisories MFSA 2026-13 and MFSA 2026-16, along with the upstream bug report at Bugzilla ID 2006199. Security practitioners should ensure affected systems are updated to these patched versions to mitigate the risk.
Details
- CWE(s)