CVE-2016-1951 in Portable Runtime
Summary
by MITRE
Multiple integer overflows in io/prprf.c in Mozilla Netscape Portable Runtime (NSPR) before 4.12 allow remote attackers to cause a denial of service (buffer overflow) or possibly have unspecified other impact via a long string to a PR_*printf function.
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Analysis
by VulDB Data Team • 05/03/2019
The vulnerability identified as CVE-2016-1951 resides within the Mozilla Netscape Portable Runtime (NSPR) library, specifically in the io/prprf.c file, affecting versions prior to 4.12. This issue represents a critical security flaw that demonstrates the dangers of improper input validation and arithmetic overflow handling in foundational software components. The NSPR library serves as a cross-platform runtime library that provides essential services for Mozilla applications including Firefox and Thunderbird, making this vulnerability particularly concerning for widespread impact.
The technical flaw manifests as multiple integer overflows that occur when processing long strings through PR_*printf functions within the NSPR library. These functions are responsible for formatted output operations and string manipulation tasks that are fundamental to application functionality. When an attacker supplies a sufficiently long string to these functions, the integer overflow conditions cause the library to miscalculate buffer sizes, leading to memory corruption. The overflow conditions can result in either a denial of service through buffer overflow or potentially more severe consequences including arbitrary code execution, depending on the specific circumstances of the overflow and the memory layout of the affected system.
The operational impact of this vulnerability extends far beyond simple denial of service, as it affects the core runtime infrastructure that powers numerous Mozilla applications and potentially other software that depends on NSPR. Attackers can exploit this weakness by crafting malicious input strings that trigger the integer overflow conditions during printf operations, which could occur in various contexts including web page processing, file handling, or network communication parsing. The vulnerability's potential for unspecified other impacts suggests that successful exploitation might lead to more serious consequences than mere service disruption, potentially enabling privilege escalation or information disclosure depending on the execution environment.
Mitigation strategies for CVE-2016-1951 primarily focus on upgrading to NSPR version 4.12 or later, which contains the necessary patches to address the integer overflow conditions. System administrators should prioritize this update across all affected environments, particularly in enterprise settings where Mozilla-based applications are deployed. Additionally, implementing input validation measures and monitoring for unusual string processing patterns can help detect potential exploitation attempts. The vulnerability aligns with CWE-190, Integer Overflow or Wraparound, and represents a classic example of how seemingly benign string handling operations can become security risks when proper bounds checking is absent. From an ATT&CK framework perspective, this vulnerability could be leveraged as part of initial access or privilege escalation tactics, particularly in environments where applications rely heavily on NSPR functionality for core operations. Organizations should also consider implementing network segmentation and application whitelisting to limit the potential impact of successful exploitation attempts.