In today's post, we'll discuss a recently discovered race condition flaw (CVE-2023-3758) found in the System Security Services Daemon (SSSD). This vulnerability may result in improper authorization issues, either granting or denying access to resources when it shouldn't. We'll provide a detailed explanation of the flaw, code snippets showcasing the issue, links to original references, and information about possible exploits.


The CVE-2023-3758 vulnerability affects the SSSD, which is a software package that provides access to identity and authentication remote resources. Among its functions, SSSD is capable of applying Group Policy Objects (GPO) to control access permissions for authenticated users.

The race condition flaw in SSSD was found in the way it applies GPO policies to authenticated users. Due to this flaw, policies may not consistently apply, thus leading to potential improper authorization issues.

Technical Details

The flaw lies in the gpo.c source file where SSSD fails to consistently apply GPO policies to authenticated users. Here's a simplified code snippet that showcases the vulnerability:

1. srv_req = sss_gpo_get_policy(...);
2. if (srv_req->gpo_state == GPO_NEW)
3. {
4.   srv_req->errno = sss_gpo_http_get_policy(file_url, &tmp_file);
5.   if (srv_req->errno)
6.   {
7.       perror("Error downloading GPO file");
8.       return srv_req->errno;
9.   }
10.  else
11.  {
12.      srv_req->gpo_data = sss_gpo_parse_file(tmp_file, policy);
13.      if (srv_req->gpo_data)
14.      {
15.          srv_req->gpo_state = GPO_OLD;
16.          srv_req->gpo_to_update = 1;
17.          srv_req->policy = policy;
18.          srv_req->policy_version++;
19.      }
20.  }
21. }

As shown in the code snippet, sss_gpo_get_policy() is called to obtain the GPO policy for the authenticated user. If the policy state is GPO_NEW, sss_gpo_http_get_policy() is called to download the GPO file.

However, due to the race condition flaw, the GPO policy may not properly apply, causing potential improper authorization issues.


Until the SSSD team fixes the vulnerability, it is recommended to implement access controls where possible and monitor the activity logs for any inconsistency in the authentication and authorization process. Additionally, users are advised to watch for any updates regarding this vulnerability and patch their SSSD installations when a fix becomes available.


As of now, there are no known exploits for this vulnerability. However, it's essential to stay aware since an attacker who manages to exploit this flaw might be able to grant themselves unauthorized access to restricted resources or deny access to legitimate users.

Original References

1. SSSD GitHub Repository: Source code for the SSSD project where the flaw is located.
2. CVE-2023-3758: Official CVE entry for this vulnerability.


CVE-2023-3758 presents a significant risk due to its potential to create improper authorization issues in environments that rely on SSSD for the application of GPO policies. Although no known exploits are available at this time, it's crucial to remain vigilant and proactively implement access controls and monitoring to mitigate the risk.

It's crucial for users to keep an eye out for updates from the SSSD team regarding this vulnerability and apply any patches or workarounds as they become available. Stay tuned for more information about this vulnerability as it becomes available.


Published on: 04/18/2024 19:15:08 UTC
Last modified on: 05/22/2024 18:15:09 UTC