CVE-2017-7826 in Firefox
Summary
by MITRE
Memory safety bugs were reported in Firefox 56 and Firefox ESR 52.4. Some of 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 < 57, Firefox ESR < 52.5, and Thunderbird < 52.5.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 11/26/2025
The vulnerability identified as CVE-2017-7826 represents a critical memory safety issue affecting Mozilla Firefox and Thunderbird applications. This vulnerability stems from multiple memory safety bugs discovered within Firefox version 56 and Firefox ESR 52.4, with implications extending to affected versions of Thunderbird. The nature of these memory safety flaws creates conditions where memory corruption can occur, potentially enabling attackers to execute arbitrary code on vulnerable systems. The vulnerability was particularly concerning because it affected widely used web browsers and email clients, making it a prime target for exploitation in real-world scenarios.
These memory safety bugs fall under the category of memory corruption vulnerabilities that are commonly classified as CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write conditions. The presence of these vulnerabilities in the browser's memory management systems creates opportunities for attackers to manipulate memory layouts and execute malicious code. The flaw manifests when the application fails to properly validate memory access operations, allowing attackers to potentially overwrite critical memory locations or read unauthorized data. The exploitation potential is significant given that these bugs were discovered in widely deployed browser versions and could be leveraged in various attack scenarios.
The operational impact of CVE-2017-7826 extends beyond simple browser compromise, as these vulnerabilities could enable attackers to gain full system control through carefully crafted web pages or email content. Attackers could potentially leverage these memory corruption issues to bypass modern security mitigations such as address space layout randomization and data execution prevention. The vulnerability affects not only end-user browsers but also enterprise environments where these applications are widely deployed, creating substantial risk for organizations that rely on Firefox or Thunderbird for their communication needs. The fact that the vulnerability affects both regular Firefox releases and the Extended Support Release versions demonstrates the widespread nature of the flaw.
Organizations should prioritize immediate patching of affected systems to mitigate the risk posed by this vulnerability. The recommended remediation involves upgrading to Firefox version 57 or later, Firefox ESR 52.5 or later, and Thunderbird 52.5 or later. Security teams should also implement network-level protections such as web application firewalls and content filtering systems to prevent exploitation attempts. Additionally, user education regarding the dangers of visiting untrusted websites or opening suspicious email attachments remains crucial. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1059.007 for command and scripting interpreter and T1203 for exploitation for client execution, making it a significant concern for defensive security operations. The vulnerability demonstrates the critical importance of maintaining up-to-date software and implementing robust patch management processes to protect against memory safety issues that can lead to complete system compromise.