CVE-2017-18258 : Security Advisory and Response
Learn about CVE-2017-18258, a vulnerability in libxml2 library allowing remote attackers to trigger a denial of service attack by consuming excessive memory with a crafted LZMA file.
The xz_head function in xzlib.c within the libxml2 library, prior to version 2.9.6, presents a vulnerability that enables remote attackers to initiate a denial of service attack through excessive memory consumption. This vulnerability occurs due to the lack of memory usage limitations enforced by the decoder functionality in the presence of a malicious LZMA file, surpassing the amount necessary for a valid file.
Understanding CVE-2017-18258
This CVE entry describes a vulnerability in the libxml2 library that could be exploited by remote attackers to cause a denial of service attack.
What is CVE-2017-18258?
The vulnerability in the xz_head function in xzlib.c within libxml2 allows remote attackers to trigger a denial of service attack by consuming excessive memory with a crafted LZMA file.
The Impact of CVE-2017-18258
The vulnerability can lead to a denial of service condition, causing affected systems to become unresponsive or crash due to high memory consumption.
Technical Details of CVE-2017-18258
This section provides more in-depth technical information about the vulnerability.
Vulnerability Description
The xz_head function in xzlib.c in libxml2 before version 2.9.6 allows remote attackers to cause a denial of service (memory consumption) via a crafted LZMA file.
Affected Systems and Versions
- Product: Not applicable
- Vendor: Not applicable
- Versions affected: Not applicable
Exploitation Mechanism
The vulnerability arises from the lack of memory usage restrictions in the decoder functionality when processing a malicious LZMA file.
Mitigation and Prevention
Protecting systems from this vulnerability requires specific actions to mitigate the risk.
Immediate Steps to Take
- Update libxml2 to version 2.9.6 or later to address the vulnerability.
- Monitor system resources for unusual memory consumption that could indicate a potential attack.
Long-Term Security Practices
- Regularly update software and libraries to patch known vulnerabilities.
- Implement network security measures to detect and block malicious traffic targeting this vulnerability.
Patching and Updates
- Apply security updates provided by the libxml2 project to fix the vulnerability and enhance system security.