CVE-2021-35516 affects Apache Commons Compress, specifically within its sevenz package. The vulnerability allows an attacker to trigger excessive memory allocation when processing specially crafted 7Z archives. This can lead to an out-of-memory error, effectively resulting in a denial of service (DoS). Given that the issue can arise from minimal input sizes, the risk to services utilizing this library is significant.
With a CVSS score of 7.5, this vulnerability is classified as high severity. Organizations that rely on affected versions of Apache Commons Compress should treat this vulnerability with urgency. The potential impact includes service outages and degraded performance, which can affect end users and business operations.
Currently, there are no known exploits in the wild, but the nature of this vulnerability suggests that it could be leveraged in denial of service attacks. Organizations are advised to closely monitor their systems and apply necessary patches to mitigate the risks associated with this vulnerability.
Organizations should prioritize patching immediately to protect against potential exploitation. For those utilizing versions 1.6 to 1.20 of Apache Commons Compress, timely updates are critical to maintaining service availability.
Vulnerability Details
The official description of CVE-2021-35516 states that when reading a specially crafted 7Z archive, the Compress library can allocate large amounts of memory, leading to an out-of-memory error even for very small inputs. This vulnerability has been assigned the CWE identifiers CWE-130 (Improper Handling of Length Parameter Inconsistency) and CWE-770 (Allocation of Resources Without Limits or Throttling).
According to the CVSS v3.1 metrics, this vulnerability has an attack vector of NETWORK, low attack complexity, and does not require privileges or user interaction. The availability impact is rated as HIGH, indicating that successful exploitation could result in significant service disruption.
Technical Analysis
The root cause of this vulnerability lies in the way Apache Commons Compress handles the 7Z archive format. Specifically, the library does not impose sufficient limits on memory allocation when processing these archives, which can lead to excessive resource consumption and ultimately crash the application. The attack vector is primarily network-based, allowing attackers to exploit the vulnerability remotely.
The attack complexity is low, meaning that an attacker with network access can exploit this vulnerability without requiring advanced skills. Additionally, no user interaction is necessary, making it easier for attackers to carry out successful denial of service attacks. The confidentiality and integrity impacts are rated as NONE, while the availability impact is HIGH, emphasizing the disruption potential.
Risk & Impact Analysis
The risk to organizations includes potential service outages, particularly for applications relying on Apache Commons Compress for archive processing. Given the prevalence of this library across various applications, the blast radius of a successful attack could be extensive. Organizations must assess their deployment environments and identify any services using affected versions of the library.
With the CVSS score indicating a high severity of 7.5, organizations should address this vulnerability in their priority patch cycle. The availability impact could severely affect business continuity, making immediate action essential.
Furthermore, the EPSS score of 0.014 indicates a low probability of exploitation in the near term, but this should not diminish the urgency for remediation. Organizations must remain vigilant and proactive in their security posture to mitigate any potential risks.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerability affects Apache Commons Compress versions 1.6 to 1.20. Organizations utilizing these versions should take immediate action to patch or upgrade to a secure version.
Mitigation & Remediation
To remediate this vulnerability, organizations should update Apache Commons Compress to a version that is not affected, specifically any version above 1.20. If an immediate upgrade is not feasible, organizations should implement workarounds such as limiting the size of 7Z archives processed by their applications.
In addition to patching, organizations should review their configurations for potential hardening measures. Network controls can also be employed to monitor and restrict access to potentially vulnerable services.
Organizations should validate remediation through penetration testing to identify similar weaknesses.
Detection Guidance
Organizations should monitor logs for unusual memory usage patterns or service interruptions indicative of potential exploitation attempts. Additionally, behavioral anomalies in service performance can be a sign of underlying issues related to this vulnerability.
AppSecure Threat Intelligence Insight
CVE-2021-35516 highlights the importance of secure coding practices, particularly in libraries that handle external data formats. The vulnerability reflects a broader trend in software development where insufficient input validation can lead to significant security issues.
Security teams must remain vigilant in their review of third-party libraries and frameworks. Regular updates and security assessments should be part of an organization's standard operating procedures.
For more insights on improving security posture, organizations can refer to our vulnerability management program and best practices for conducting penetration testing effectively.
Additionally, the significance of this vulnerability emphasizes the need for an organization-wide approach to security, incorporating both development and operational practices to ensure resilience against similar threats.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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