CVE-2026-4709
Published: 24 March 2026
Summary
CVE-2026-4709 is a high-severity Improper Check for Unusual or Exceptional Conditions (CWE-754) vulnerability in Mozilla Firefox. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 36.9th 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 RA-5 (Vulnerability Monitoring and Scanning) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-4709 is a vulnerability stemming from incorrect boundary conditions in the Audio/Video: GMP component of Mozilla products. It affects Firefox versions prior to 149, Firefox ESR versions prior to 115.34 and 140.9, Thunderbird versions prior to 149 and 140.9. The issue is classified under CWE-754 (Improper Check for Unusual or Exceptional Conditions) and carries a CVSS v3.1 base score of 7.5.
Remote attackers require no privileges or user interaction to exploit this vulnerability over the network with low complexity. Successful exploitation results in high-impact denial of service, such as application crashes, with no impact on confidentiality or integrity and unchanged scope.
Mozilla security advisories (MFSA 2026-20, 2026-21, and 2026-22) and related Bugzilla entries detail the patch status, confirming fixes in the specified Firefox and Thunderbird versions. Security practitioners should prioritize updating affected installations to mitigate exposure.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-14834
Vulnerability details
Incorrect boundary conditions in the Audio/Video: GMP component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Remote unauthenticated exploitation of the boundary condition flaw in the GMP media component directly results in application crashes, mapping to Endpoint DoS via application/system exploitation.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly mandates timely remediation of known software flaws like this boundary condition vulnerability in the GMP component via vendor patches such as those in Firefox 149 and Thunderbird 149.
Requires vulnerability scanning to identify deployments of vulnerable Firefox and Thunderbird versions affected by this GMP boundary condition issue.
Ensures monitoring of security advisories like MFSA 2026-20, 2026-21, and 2026-22 to facilitate prompt patching of this CVE.
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 (3 rules)
- V-248574 YUM must be configured to prevent the installation of patches, service packs, device drivers, or OL 8 system components that have not been digitally signed using a certificate that is recognized and approved by the organization. via CWE-754
- V-248573 The OL 8 file integrity tool must notify the system administrator (SA) when changes to the baseline configuration or anomalies in the operation of any security functions are discovered within an organizationally defined frequency. via CWE-754
- V-248575 OL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. via CWE-754
Oracle Linux 9 (1 rule)
- V-271452 OL 9 must use a Linux Security Module configured to enforce limits on system services. via CWE-754