CVE-2018-5145 in Firefox
Summary
by MITRE
Memory safety bugs were reported in Firefox ESR 52.6. These bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code. This vulnerability affects Firefox ESR < 52.7 and Thunderbird < 52.7.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 11/26/2025
The vulnerability identified as CVE-2018-5145 represents a critical memory safety issue within Mozilla Firefox Extended Support Release version 52.6 and related Thunderbird email client versions. This classification stems from the discovery of multiple memory corruption flaws that demonstrate potential for arbitrary code execution when exploited by malicious actors. The vulnerability affects organizations and individuals using older versions of these browsers and email clients, creating significant security risks for users who have not updated to patched versions. The memory safety bugs identified in this vulnerability are particularly concerning because they exhibit characteristics consistent with exploitable conditions that could be leveraged by attackers to gain unauthorized control over affected systems.
These memory safety vulnerabilities are categorized under CWE-122, which describes "Heap-based Buffer Overflow" conditions, and CWE-125, which covers "Out-of-bounds Read" scenarios. The technical nature of these flaws suggests that they involve improper handling of memory allocations and deallocations within the browser's rendering engine and JavaScript interpreter. When Firefox processes certain web content or email messages, these memory corruption issues can lead to unpredictable behavior where attacker-controlled data might overwrite critical memory regions. The vulnerability specifically impacts Firefox ESR versions prior to 52.7 and Thunderbird versions prior to 52.7, indicating that these were the last releases before the memory safety patches were implemented. The nature of these memory corruption bugs aligns with ATT&CK technique T1059.007, which involves the execution of malicious code through web browsers, and T1059.001 for command and scripting interpreter usage.
The operational impact of CVE-2018-5145 extends beyond simple browser compromise, as it could enable attackers to establish persistent access to user systems through browser-based attacks. Organizations running unpatched Firefox ESR 52.6 installations face significant risk of data breaches, system compromise, and potential lateral movement within their networks. The vulnerability's potential for arbitrary code execution means that attackers could install malware, steal credentials, or perform other malicious activities without user interaction. Users who regularly access the internet through Firefox or Thunderbird remain at risk until they update to versions 52.7 or later, as these older versions contain the exploitable memory safety flaws. The vulnerability's exploitation potential is heightened by the fact that many organizations maintain older browser versions for compatibility reasons, creating extended attack surfaces that adversaries can target.
Mitigation strategies for CVE-2018-5145 primarily focus on immediate patching and system updates to Firefox ESR 52.7 and Thunderbird 52.7 releases. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive updates promptly, particularly those running legacy versions of these applications. Security teams should also consider implementing network monitoring to detect potential exploitation attempts through unusual browser behavior or network connections. Additional protective measures include deploying web application firewalls, implementing strict browser security policies, and educating users about the importance of keeping their software updated. The vulnerability highlights the critical importance of maintaining current software versions, as older releases often contain unpatched security flaws that can be exploited by threat actors. Organizations should also consider implementing sandboxing technologies and browser hardening measures to reduce the potential impact of successful exploitation attempts. Regular vulnerability assessments and penetration testing can help identify systems running vulnerable versions and ensure proper remediation occurs before attackers can exploit these memory safety issues.