CVE-2026-15809
Description
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.
Statement
This Important flaw in CRI-O allows for arbitrary line injection into a container's /etc/passwd file. An attacker capable of setting container environment variables can bypass a previous fix (CVE-2022-4318) by supplying a real newline character in the HOME environment variable, potentially leading to privilege escalation within the affected container. This risk is present in environments where untrusted users can influence container environment variable settings.
Mitigation
Restrict access to users who can create or modify container workloads through appropriate RBAC permissions, apply security controls such as Security Context Constraints (SCCs) to limit privilege escalation, and enforce policies to run containers with reduced privileges (for example, as non-root) to reduce the impact of potential exploitation. Enable SELinux on affected nodes and consider admission controls to prevent potentially unsafe workload configurations.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.8 | N/A | 7.8 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
Format string problems allow for information disclosure which can severely simplify exploitation of the program.
Integrity,Confidentiality,Availability
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Format string problems can result in the execution of arbitrary code, buffer overflows, denial of service, or incorrect data representation.
Acknowledgements
Red Hat would like to thank Nebojša Jaćović (Independent Security Researcher) for reporting this issue.
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