CVE-2017-7779 in Firefox
Summary
by MITRE
Memory safety bugs were reported in Firefox 54, Firefox ESR 52.2, and Thunderbird 52.2. 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 Thunderbird < 52.3, Firefox ESR < 52.3, and Firefox < 55.
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Analysis
by VulDB Data Team • 11/26/2025
The vulnerability identified as CVE-2017-7779 represents a critical memory safety issue affecting Mozilla's Firefox browser and Thunderbird email client across multiple versions. This vulnerability stems from memory safety bugs that were discovered in the software's handling of memory allocation and deallocation processes. The affected versions include Firefox 54 and Firefox ESR 52.2, along with Thunderbird 52.2, where the underlying memory management mechanisms exhibited flaws that could lead to unpredictable behavior and potential exploitation by malicious actors.
These memory safety bugs manifest as issues in how the applications manage memory resources during normal operation and when processing complex data structures. The vulnerability's nature suggests that attackers could potentially manipulate memory layouts or trigger memory corruption conditions that would allow them to execute arbitrary code on affected systems. The presence of evidence indicating memory corruption demonstrates that the flaws are not merely theoretical but have demonstrated potential for actual exploitation in real-world scenarios.
The operational impact of this vulnerability extends beyond simple functionality issues to encompass serious security risks for users of affected software versions. When memory corruption occurs, it can lead to application crashes, data loss, or more critically, provide attackers with opportunities to gain unauthorized control over systems. The vulnerability affects users who have not yet updated to the patched versions, specifically those running Thunderbird versions earlier than 52.3, Firefox ESR versions earlier than 52.3, and Firefox versions earlier than 55. The potential for arbitrary code execution makes this vulnerability particularly dangerous in environments where users may be exposed to malicious content or where privilege escalation could occur.
The technical characteristics of this vulnerability align with common memory safety issues categorized under CWE-119 and CWE-121, which address buffer overflows and memory corruption conditions. These weaknesses provide attackers with pathways to manipulate memory contents and potentially execute malicious code with the privileges of the affected application. The ATT&CK framework would classify this vulnerability under the T1059.007 technique for "Command and Scripting Interpreter: JavaScript" as attackers could leverage the memory corruption to execute JavaScript code, or under T1068 for "Exploitation for Privilege Escalation" when the memory corruption leads to elevated system access.
Organizations and individuals should prioritize immediate remediation by updating to the patched versions of affected software, specifically Thunderbird 52.3, Firefox ESR 52.3, and Firefox 55. The patch addresses the underlying memory safety issues through improved memory management and validation procedures. Additionally, implementing network security controls such as web application firewalls and content filtering systems can provide additional layers of protection while waiting for full deployment of patches. System administrators should also monitor for any signs of exploitation attempts and maintain comprehensive logging of application behavior to detect potential abuse of this vulnerability.