CVE-2026-15809 in CRI-O
Summary
by MITRE • 07/15/2026
A flaw was found in CRI-O. The fix for a previous vulnerability (CVE-2022-4318) was incorrect, allowing it to be bypassed. An attacker capable of setting environment variables on a container can inject a newline character into the HOME environment variable. This issue allows the addition of arbitrary lines into /etc/passwd by use of a specially crafted environment variable.
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Analysis
by VulDB Data Team • 07/15/2026
This vulnerability in CRI-O represents a critical security flaw that emerged from an improper remediation of a previously identified weakness. The original CVE-2022-4318 was addressed through what appeared to be a sufficient fix, but subsequent analysis revealed that the solution contained a fundamental flaw that permitted attackers to circumvent the protective measures. This type of vulnerability falls under CWE-170 which specifically addresses issues related to improper handling of input data containing newline characters, particularly in contexts where such characters can be exploited to manipulate system configuration files or inject malicious content.
The technical mechanism behind this vulnerability involves the manipulation of environment variables within containerized environments, specifically targeting the HOME environment variable. When an attacker gains the capability to set environment variables on a container, they can craft a specially formatted value that includes newline characters. This seemingly innocuous input manipulation becomes dangerous when the container runtime processes these environment variables without proper sanitization or validation. The vulnerability exploits the fact that CRI-O does not adequately validate or sanitize environment variable values before processing them, particularly when these variables are used to influence system configuration files.
The operational impact of this vulnerability is severe as it directly enables privilege escalation and persistent access within containerized environments. By injecting newline characters into the HOME environment variable, an attacker can effectively manipulate the /etc/passwd file by appending arbitrary lines that can be interpreted by the system's user management mechanisms. This could result in the creation of new user accounts with elevated privileges or modification of existing user permissions, fundamentally compromising the security boundaries that containerization is designed to maintain. The attack vector is particularly concerning because environment variable manipulation is a common practice in container orchestration and deployment scenarios, making this vulnerability exploitable in numerous real-world configurations.
The exploitation of this vulnerability demonstrates characteristics aligned with ATT&CK technique T1548.003 which covers abuse of sudo privileges and T1068 which involves exploit for privilege escalation. The flaw essentially allows attackers to bypass the intended security controls that should prevent unauthorized modifications to system user databases. Organizations utilizing CRI-O as their container runtime are at significant risk, particularly those with less stringent access controls or those running containers with elevated privileges. The vulnerability's impact extends beyond individual containers to potentially compromise entire container orchestration platforms, especially when combined with other exploitation techniques that leverage container escape mechanisms.
Mitigation strategies should focus on immediate patch application if available, but also require comprehensive environment variable sanitization practices within container deployments. System administrators should implement strict validation of environment variables before they are processed by container runtimes, particularly those that might influence system configuration files or user account management. Additional protective measures include implementing runtime monitoring for suspicious environment variable modifications, restricting the ability to set arbitrary environment variables in production containers, and conducting regular security audits of container configurations. Organizations should also consider implementing network segmentation and privilege separation to limit the potential impact of successful exploitation attempts. The vulnerability highlights the importance of thorough testing and validation of security patches, particularly when addressing complex issues that involve configuration file manipulation and environment variable handling within containerized environments.