CVE-2016-3189 in bzip2
Summary
by MITRE
Use-after-free vulnerability in bzip2recover in bzip2 1.0.6 allows remote attackers to cause a denial of service (crash) via a crafted bzip2 file, related to block ends set to before the start of the block.
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Analysis
by VulDB Data Team • 06/09/2025
The vulnerability identified as CVE-2016-3189 represents a critical use-after-free flaw within the bzip2recover utility component of the bzip2 compression library version 1.0.6. This issue specifically targets the recovery tool designed to reconstruct damaged bzip2 files, creating a scenario where remote attackers can exploit malformed input to trigger system instability. The vulnerability resides in the bzip2 library's handling of corrupted archive data during the recovery process, making it particularly dangerous as it can be triggered by simply processing a maliciously crafted bzip2 file without requiring any special privileges or user interaction beyond the standard decompression process.
The technical root cause of this vulnerability stems from improper memory management within the bzip2recover utility's block processing logic. When the utility encounters a bzip2 file with block end markers positioned before the block's actual start point, the program fails to properly validate these malformed references before attempting to access or free memory locations that may have already been deallocated. This fundamental flaw in input validation creates a use-after-free condition where the program attempts to reference memory that has been freed, leading to unpredictable behavior and ultimately system crashes. The vulnerability is classified under CWE-416, which specifically addresses the use of freed memory, and aligns with ATT&CK technique T1499.004 for network denial of service attacks through file processing.
The operational impact of CVE-2016-3189 extends beyond simple system crashes, as it can be leveraged in various attack scenarios that compromise system availability and stability. Remote attackers can craft malicious bzip2 files that, when processed by vulnerable systems, will cause the bzip2recover utility to crash and potentially expose underlying system memory structures. This vulnerability affects any system running bzip2 version 1.0.6 or earlier, including servers, workstations, and embedded devices that rely on bzip2 for data compression and decompression. The attack vector is particularly concerning because it requires no authentication or special privileges, making it accessible to any attacker who can deliver a malicious file to a vulnerable system. Systems that automatically process or decompress user-uploaded files, such as web servers, email servers, or file transfer applications, become especially vulnerable to this type of denial of service attack.
Mitigation strategies for CVE-2016-3189 primarily focus on immediate software updates and input validation improvements. Organizations should prioritize upgrading to bzip2 version 1.0.7 or later, where the vulnerability has been addressed through proper memory management and input validation. Additionally, system administrators should implement strict file validation procedures for any bzip2 files processed by automated systems, particularly those receiving untrusted input. Network-level protections such as file type filtering and content scanning can provide additional layers of defense against exploitation attempts. The fix implemented in the patched versions includes enhanced validation of block boundary conditions and proper memory deallocation procedures that prevent the use-after-free scenario from occurring. Security monitoring should also include detection of unusual crash patterns or resource consumption spikes that may indicate exploitation attempts targeting this vulnerability.