CVE-2026-68744
Description
A flaw was found in SSSD. The sss_nss_protocol_fill_initgr() function in the NSS responder pre-allocates reply space for all group entries but does not shrink the packet when groups are skipped, causing uninitialized heap bytes to be transmitted to the client. A local attacker can exploit this to disclose cached directory data and heap layout information from the sssd_nss process.
Statement
This issue can only be triggered by a local attacker who can connect to the SSSD NSS responder unix socket. The disclosed data is limited to directory-level information and process heap layout from the sssd_nss process. Credentials, hashes, and tickets reside in separate sssd_pam and sssd_be processes and are not exposed by this flaw. Much of the directory data may already be obtainable via legitimate NSS queries depending on the deployment. The primary security concern is disclosure of heap pointers that could assist ASLR bypass if chained with a separate memory-corruption vulnerability.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
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 | 3.3 | N/A | 3.3 |
| 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 | Low | N/A | Low |
| Integrity Impact | None | N/A | None |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Red Hat CVSS v3 Score Explanation
Local information disclosure of uninitialized sssd_nss heap via initgroups reply. Leaks directory-level data and heap pointers; no credentials.
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory; Read Application Data
When reusing a resource such as memory or a program variable, the original contents of that resource may not be cleared before it is sent to an untrusted party.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
The uninitialized resource may contain values that cause program flow to change in ways that the programmer did not intend.
Acknowledgements
Red Hat would like to thank Vivek Parikh (BreachX Zero Day Labs) for reporting this issue.
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