Overview
CVE-2026-38638 is a Denial of Service (DoS) vulnerability identified in the relibc library, a part of the Redox operating system. This vulnerability resides in the with_argv function located in the /unistd/mod.rs file. The Common Vulnerability Scoring System (CVSS) score for this vulnerability is 7.5, categorizing it as high severity. Understanding this vulnerability is crucial for developers and security practitioners working with the Redox OS or similar environments.
Understanding the Vulnerability / Threat
Root Cause Analysis
The root cause of CVE-2026-38638 is an issue in the with_argv function of relibc. This function fails to properly handle crafted inputs, leading to a Denial of Service (DoS) condition. The vulnerability is classified under CWE-400, which pertains to Uncontrolled Resource Consumption.
Attack Surface & Vector
The attack surface for this vulnerability is network-adjacent, as indicated by the CVSS vector string 'AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'. This means that an attacker can exploit this vulnerability remotely without any prerequisites. The attack complexity is low, and no user interaction is required.
Exploitation Mechanics — Scenario Walkthrough
Scenario: Exploiting CVE-2026-38638 for Denial of Service
1. Initial Position: The attacker has network access to the target system running Redox OS with the vulnerable relibc library.
2. Triggering the Flaw: The attacker crafts a malicious input designed to exploit the with_argv function in relibc. This crafted input could be a specially designed argument or set of arguments passed to the function.
3. What Breaks: When the with_argv function processes the crafted input, it fails to handle it properly due to inadequate checks or resource management. This failure leads to an uncontrolled consumption of resources (such as memory or CPU), causing the system to become unresponsive or crash.
4. Attacker's Prize: The attacker successfully triggers a Denial of Service condition. The system or application becomes unavailable, impacting users and potentially causing significant disruption.
Real-World Impact
The real-world impact of CVE-2026-38638 can be significant, especially in environments where the Redox OS or systems using the relibc library are deployed. An attacker exploiting this vulnerability could cause critical systems to become unresponsive, leading to operational disruptions, loss of service, and potential financial impacts.
Detection & Defense
Immediate Mitigations
- Upgrade to a patched version of relibc if available. The Redox OS community or relevant vendors may release updates addressing this vulnerability.
- Implement network security measures to restrict access to vulnerable systems until patches can be applied.
Detection Strategies
- Monitor system logs for unusual patterns of resource consumption or service unavailability.
- Implement intrusion detection systems (IDS) that can identify and alert on potential exploitation attempts.
- Regularly review and update security monitoring rules to detect novel exploitation techniques.
Long-Term Hardening
- Regularly update and patch systems and libraries, including relibc, to prevent exploitation of known vulnerabilities.
- Implement a robust security testing and validation process for all software components, including those from third-party vendors.
- Consider adopting a defense-in-depth strategy that includes multiple layers of security controls to mitigate the impact of potential breaches.
Key Takeaways
- CVE-2026-38638 is a high-severity DoS vulnerability in the relibc library used in Redox OS.
- The vulnerability allows for remote exploitation without authentication, leading to potential service disruptions.
- Immediate mitigations include upgrading to patched versions and restricting access to vulnerable systems.
- Detection strategies involve monitoring for unusual resource consumption patterns and implementing IDS.
- Long-term hardening includes regular updates, security testing, and a defense-in-depth approach.
Sources
- National Vulnerability Database (NVD) - CVE-2026-38638