CVE-2019-15921
Description
A flaw was found in the genl_register_family function in the Linux kernel. An attacker able to induce the error conditions could use this flaw to crash the system. The highest threat from this vulnerability is to system availability.
Statement
This issue is rated as having Low impact because of the preconditions needed to trigger the error/resource cleanup code path (system-wide out-of-memory condition, high privileges or physical access). The generic netlink is a way for kernel modues to easily communicate with userspace using netlink. genl_register_family is thus called by kernel modules (code) only and it's hard for an attacker to invoke (module reloads?) it let alone fail on the right place.
Mitigation
Mitigation for this issue is either not available or the currently available options don't 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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4.7 | 4.7 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | Low | Low | 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:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Red Hat CVSS v3 Score Explanation
This issue is in generic netlink code, not network code, hence AV:L. AC:H because the generic netlink is a way for kernel modues to easily communicate with userspace using netlink. genl_register_family is thus called by kernel modules (code) only and it's hard for an attacker to invoke (module reloads?) it let alone fail on the right place. This is only memory leak (theoretically leading to available memory exhaustion) not a privilege escalation, hence CI:N and A:H.
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Instability; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
Most memory leaks result in general product reliability problems, but if an attacker can intentionally trigger a memory leak, the attacker might be able to launch a denial of service attack (by crashing or hanging the program) or take advantage of other unexpected program behavior resulting from a low memory condition.
Other
Technical Impact: Reduce Performance
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