CVE-1999-0425 in Communicator
Summary
by MITRE
talkback in Netscape 4.5 allows a local user to kill an arbitrary process of another user whose Netscape crashes.
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Analysis
by VulDB Data Team • 04/19/2026
The vulnerability identified as CVE-1999-0425 affects Netscape 4.5 web browser and represents a critical local privilege escalation issue within the talkback component. This flaw enables a local attacker to terminate arbitrary processes belonging to other users when the Netscape browser crashes, creating a significant security risk in multi-user environments. The vulnerability stems from insufficient process isolation mechanisms and improper privilege handling within the browser's crash handling system. When Netscape encounters a crash scenario, the talkback functionality fails to properly validate process ownership, allowing malicious local users to exploit this weakness to target processes owned by different system users.
The technical implementation of this vulnerability resides in the inter-process communication mechanisms and process management functions within Netscape's talkback subsystem. The flaw occurs during the browser's crash recovery phase where the system attempts to clean up resources and terminate associated processes. However, the validation checks are inadequate, permitting unauthorized process termination based on process identifiers rather than proper ownership verification. This weakness falls under the category of improper privilege management and process control violations, aligning with CWE-276 which addresses inadequate privilege management and CWE-782 which covers exposure of process control interfaces. The vulnerability demonstrates a classic case of insufficient access control in multi-user systems where process termination privileges are not properly restricted.
The operational impact of this vulnerability extends beyond simple process termination, potentially enabling more sophisticated attacks such as service disruption, privilege escalation, or even system compromise. An attacker could target critical system processes, user sessions, or application services to cause denial of service conditions or gain unauthorized access to sensitive data. The vulnerability is particularly dangerous in shared hosting environments, multi-user workstations, or enterprise settings where multiple users interact with the same system. Attackers could leverage this weakness to disrupt legitimate user activities, terminate security monitoring processes, or create conditions favorable for further exploitation. This vulnerability directly impacts the principle of least privilege and demonstrates how local privilege escalation can occur through seemingly benign system components.
Mitigation strategies for CVE-1999-0425 require immediate patching of the Netscape 4.5 browser to address the flawed process management logic. Organizations should implement proper process isolation mechanisms and ensure that process termination privileges are strictly enforced based on user ownership and system permissions. The fix should include enhanced validation of process identifiers and proper privilege checking before any process termination operations occur. System administrators should also consider implementing additional monitoring and logging of process termination activities to detect potential exploitation attempts. Security hardening measures such as restricting local user access to critical system processes and implementing proper access control lists can provide additional defense layers. According to ATT&CK framework, this vulnerability maps to T1055 for process injection and privilege escalation techniques, while also relating to T1496 for resource hijacking and system disruption. Regular security assessments and vulnerability scanning should be conducted to identify similar weaknesses in other browser components or system services that may present similar privilege escalation vectors. The remediation process should include comprehensive testing to ensure that the fix does not introduce regressions in legitimate browser functionality while maintaining proper security controls.