CVE-2026-2769
Published: 24 February 2026
Summary
CVE-2026-2769 is a high-severity Use After Free (CWE-416) vulnerability in Mozilla Firefox. Its CVSS base score is 8.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Drive-by Compromise (T1189); ranked at the 33.7th 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 RA-5 (Vulnerability Monitoring and Scanning).
Deeper analysis
CVE-2026-2769 is a use-after-free vulnerability (CWE-416) in the Storage: IndexedDB component of Mozilla Firefox and Thunderbird products. It affects versions prior to the fixed releases, including Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8. The flaw carries a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H), indicating high severity due to its potential for significant impact across confidentiality, integrity, and availability.
The vulnerability can be exploited by a remote attacker with no privileges required, via low-complexity attacks that necessitate user interaction, such as visiting a malicious webpage. Successful exploitation could allow arbitrary code execution within the browser sandbox, data theft from IndexedDB storage, or denial-of-service through crashes, potentially compromising user data or enabling further attacks if chained with sandbox escapes.
Mozilla's security advisories (MFSA 2026-13 through 2026-16) and the associated Bugzilla entry detail the patch deployments in the listed versions, recommending immediate upgrades to mitigate the issue. No workarounds are specified beyond applying the updates.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-8469
Vulnerability details
Use-after-free in the Storage: IndexedDB 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 in browser IndexedDB enables drive-by compromise via malicious webpage (T1189) and direct exploitation for client-side arbitrary code execution (T1203).
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Requires timely identification, reporting, and patching of flaws like the use-after-free in Firefox's IndexedDB component, directly aligning with Mozilla's upgrade recommendation to fixed versions.
Implements memory protections such as ASLR and stack canaries that mitigate use-after-free vulnerabilities by preventing unauthorized code execution in the browser's sandboxed IndexedDB process.
Enables scanning of endpoints to identify systems running vulnerable Firefox or Thunderbird versions affected by CVE-2026-2769 prior to exploitation.
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