CVE-2023-5870
Description
A flaw was found in PostgreSQL involving the pg_cancel_backend role that signals background workers, including the logical replication launcher, autovacuum workers, and the autovacuum launcher. Successful exploitation requires a non-core extension with a less-resilient background worker and would affect that specific background worker only. This issue may allow a remote high privileged user to launch a denial of service (DoS) attack.
Statement
Although the NVD assigns this issue a Moderate rating, Red Hat classifies it as Low severity because the practical impact is limited and requires multiple specific conditions. The vulnerability allows a privileged database role (pg_signal_backend) to send signals to certain background worker processes. However, PostgreSQL’s core background workers are designed to safely handle such signals and automatically recover without disrupting the database service.
For a denial-of-service condition to occur, the system must be running a non-core extension that introduces a custom background worker which is not designed to restart safely after receiving a signal. In other words, the issue does not affect standard PostgreSQL installations and only impacts specialized configurations using third-party extensions. Even in affected scenarios, the impact is limited to disruption of a specific auxiliary background task and does not result in complete database failure, data loss, or compromise of confidentiality or integrity.
Because exploitation requires a high-privileged user and affects only certain non-default configurations with limited operational impact, Red Hat considers the real-world risk to be Low.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 2.2 | 4.4 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | High | High | 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 | Low | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:L
NVD: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
If an attacker can trigger the allocation of the limited resources, but the number or size of the resources is not controlled, then the most common result is denial of service. This would prevent valid users from accessing the product, and it could potentially have an impact on the surrounding environment, i.e., the product may slow down, crash due to unhandled errors, or lock out legitimate users. For example, a memory exhaustion attack against an application could slow down the application as well as its host operating system.
Access Control,Other
Technical Impact: Bypass Protection Mechanism; Other
In some cases it may be possible to force the product to "fail open" in the event of resource exhaustion. The state of the product -- and possibly the security functionality - may then be compromised.
Acknowledgements
Upstream acknowledges Hemanth Sandrana and Mahendrakar Srinivasarao as the original reporters.
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