CVE-2026-2772
Published: 24 February 2026
Summary
CVE-2026-2772 is a critical-severity Use After Free (CWE-416) vulnerability in Mozilla Firefox. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Drive-by Compromise (T1189); ranked at the 37.3th 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-2 (Flaw Remediation) and SC-39 (Process Isolation).
Deeper analysis
CVE-2026-2772 is a use-after-free vulnerability (CWE-416) in the Audio/Video: Playback component of Mozilla Firefox and Thunderbird. It affects versions of Firefox prior to 148, Firefox ESR prior to 115.33 and 140.8, and Thunderbird prior to 148 and 140.8. The vulnerability carries a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), indicating critical severity due to its potential for severe impact across confidentiality, integrity, and availability.
An unauthenticated attacker can exploit this vulnerability remotely over the network with low complexity and no user interaction required. Successful exploitation could allow the attacker to achieve high-impact effects, including arbitrary code execution, data corruption, or denial of service on the affected browser or email client.
Mozilla's security advisories (MFSA 2026-13 through 2026-16) and the associated Bugzilla entry detail the fix applied in the listed versions. Mitigation involves updating to Firefox 148, Firefox ESR 115.33 or 140.8, Thunderbird 148, or Thunderbird 140.8 as soon as possible to address the use-after-free issue in the playback component.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-8492
Vulnerability details
Use-after-free in the Audio/Video: Playback component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Use-after-free RCE in browser/email client media playback enables remote arbitrary code execution (no UI required), directly mapping to drive-by compromise via malicious web content and exploitation for client execution.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly mandates timely identification, reporting, and remediation of flaws like this use-after-free vulnerability through patching to updated Firefox and Thunderbird versions.
Implements memory protection mechanisms such as ASLR and DEP that mitigate exploitation of use-after-free errors in the audio/video playback component.
Provides process isolation via browser sandboxing to limit the impact of arbitrary code execution from the use-after-free vulnerability.
Hardening callouts derived
Configuration rules from DISA STIG baselines that reduce the attack surface for weaknesses of the type cited by this CVE. Derived transitively via CVE→CWE→STIG over `controls_xwalks` (authoritative rows only).
Oracle Linux 8 (1 rule)
- V-248592 OL 8 must clear memory when it is freed to prevent use-after-free attacks. via CWE-416
RHEL 8 (1 rule)
- V-230279 RHEL 8 must clear memory when it is freed to prevent use-after-free attacks. via CWE-416
RHEL 9 (1 rule)
- V-257794 RHEL 9 must clear memory when it is freed to prevent use-after-free attacks. via CWE-416