Critical Security Flaw in acl Package: Symlink Traversal Vulnerabilities
Summary
ALSA-2026:42736: Important: acl security update. Affects acl versions < 2.4.0-1.el9_8. Fixed in 2.4.0-1.el9_8. How to fix ↓
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Background
The acl package in AlmaLinux provides essential utilities for managing Access Control Lists (ACLs), which allow for fine-grained control over file and directory permissions. The package includes tools such as getfacl and setfacl, which are crucial for users needing to define specific access rights. However, vulnerabilities have been identified in this package that could lead to privilege escalation and unauthorized access.
Vulnerability Detail
The acl package has two significant vulnerabilities: CVE-2026-54369 and CVE-2026-54370. The first vulnerability allows for symlink traversal privilege escalation through libacl functions, potentially enabling attackers to gain unauthorized access to sensitive files. The second vulnerability involves a Time-of-Check to Time-of-Use (TOCTOU) issue with the getfacl and setfacl utilities, which can also lead to unauthorized access. Both vulnerabilities stem from improper handling of symbolic links, making them critical security concerns that need immediate attention.
How To Fix
Minimum fixed version
2.4.0-1.el9_8
This is the first release that contains the fix.
sudo dnf update aclTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary measure, you can restrict access to the affected utilities (getfacl and setfacl) until the package is updated. This can be done by changing the permissions of these files to limit their execution by unprivileged users. Use the following command: 'chmod 700 /usr/bin/getfacl /usr/bin/setfacl'.
Conclusion
The acl package vulnerabilities pose significant security risks that can lead to unauthorized access and privilege escalation. It is crucial to update to the patched version as soon as possible and implement temporary workarounds to mitigate risks. Regular monitoring for vulnerabilities is essential to maintain system security.
See every vulnerability recorded for acl →
FAQ
These vulnerabilities can lead to privilege escalation, allowing unauthorized users to access sensitive files and directories.
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Implement the workaround by restricting access to the affected utilities until you can perform the update.
While specific exploits may not be publicly available, the nature of the vulnerabilities suggests that they could be exploited by attackers to gain unauthorized access.
Regularly monitor your packages and dependencies for vulnerabilities, ideally using tools like Vulert that provide real-time alerts.
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