CVE-2026-4713
Published: 24 March 2026
Summary
CVE-2026-4713 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 34.8th 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-2 (Flaw Remediation) and SC-5 (Denial-of-service Protection).
Deeper analysis
CVE-2026-4713 is a vulnerability involving incorrect boundary conditions in the Graphics component of Mozilla products. It affects Firefox prior to version 149, Firefox ESR prior to 140.9, Thunderbird prior to 149, and Thunderbird prior to 140.9. The issue is classified under CWE-754 (Improper Check for Unusual or Exceptional Conditions) and received a CVSS v3.1 base score of 7.5, rated High severity due to its network accessibility, low attack complexity, lack of required privileges or user interaction, and potential for high availability impact without affecting confidentiality or integrity.
An unauthenticated attacker can exploit this vulnerability remotely over the network with low complexity and no user interaction required. Successful exploitation leads to a denial-of-service condition, such as application crashes or resource exhaustion in the affected Graphics component, disrupting browser or email client functionality for the targeted user.
Mozilla's security advisories (MFSA 2026-20, 2026-22, 2026-23, and 2026-24) and the associated Bugzilla entry (bug 2018113) detail the patches that resolve the issue. Users should update to Firefox 149, Firefox ESR 140.9, Thunderbird 149, or Thunderbird 140.9 to mitigate the vulnerability.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-14841
Vulnerability details
Incorrect boundary conditions in the Graphics component. This vulnerability was fixed in Firefox 149, 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 graphics boundary condition flaw directly causes application crashes or resource exhaustion (high availability impact), matching T1499.004 Application or System Exploitation for client-side DoS.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Requires timely identification, reporting, and patching of software flaws like the incorrect boundary conditions in the Graphics component, as addressed in Firefox 149 and Thunderbird 149 updates.
Ensures receipt and implementation of security advisories such as Mozilla MFSA 2026-20 through 2026-24, prompting updates to mitigate the vulnerability.
Protects against denial-of-service effects like application crashes or resource exhaustion triggered by remote exploitation of the Graphics component boundary flaw.
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