CVE-2021-36085 : What You Need to Know

The CIL compiler in SELinux 3.2 has a use-after-free vulnerability, potentially leading to code execution or denial of service attacks.

Understanding CVE-2021-36085

This CVE describes a critical vulnerability in SELinux 3.2 related to a use-after-free issue in the CIL compiler.

What is CVE-2021-36085?

The vulnerability in SELinux 3.2 allows attackers to trigger a use-after-free condition in certain compiler functions, which can be exploited for malicious purposes.

The Impact of CVE-2021-36085

If exploited, CVE-2021-36085 could result in arbitrary code execution or denial of service, posing a significant risk to the security and integrity of affected systems.

Technical Details of CVE-2021-36085

This section delves into the specifics of the vulnerability, affected systems, and exploitation mechanisms.

Vulnerability Description

The use-after-free vulnerability manifests in the __cil_verify_classperms function within SELinux 3.2, triggered by calls from __verify_map_perm_classperms and hashtab_map, making systems susceptible to exploitation.

Affected Systems and Versions

SELinux 3.2 installations are impacted by this vulnerability, with specific versions exhibiting the use-after-free issue that can be leveraged by threat actors.

Exploitation Mechanism

Attackers can exploit CVE-2021-36085 by crafting malicious inputs to trigger the use-after-free condition, potentially gaining unauthorized access or disrupting system operations.

Mitigation and Prevention

To safeguard systems from CVE-2021-36085, immediate steps should be taken along with long-term security practices and timely patching.

Immediate Steps to Take

Update SELinux to the latest patched version to mitigate the vulnerability.
Monitor system logs for any suspicious activities indicating exploitation attempts.

Long-Term Security Practices

Implement strict input validation mechanisms to prevent malformed inputs.
Conduct regular security assessments and audits to proactively identify and address vulnerabilities.

Patching and Updates

Stay informed about security advisories and promptly apply patches released by SELinux to address CVE-2021-36085.