CVE-2019-14847
Description
A flaw was found in samba versions 4.0.0 through 4.10.0. An attacker can crash AD DC LDAP server via dirsync resulting in denial of service. Privilege escalation is not possible with this issue.
Statement
This flaw does not affect the version of samba shipped with Red Hat Enterprise Linux because there is no support for samba as Active Directory Domain Controller.
Mitigation
By default, the supported versions of Samba impacted by this issue run using the "standard" process model, which is unaffected. This is controlled by the -M or --model parameter to the samba binary. Unsupported Samba versions before Samba 4.7 use a single process for the LDAP server, and so are impacted. Samba 4.8, 4.9, and 4.10 are impacted if -M prefork or -M single is used. To mitigate this issue, select -M standard (the default).
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 | 4.9 | 4.9 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | High | High | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
Acknowledgements
Red Hat would like to thank the Samba project for reporting this issue. Upstream acknowledges Adam Xu as the original reporter.
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