CVE-2020-8492
Description
An uncontrolled resource consumption vulnerability was discovered in python in the class AbstractBasicAuthHandler, due to the kind of regular expression used while handling an authentication request in the http_error_auth_reqed method. Client applications that use, directly or indirectly, AbstractBasicAuthHandler to connect to a malicious server may be vulnerable to this flaw, which would cause an uncontrolled use of CPU resources on the victim's system, resulting in a Denial of Service.
Statement
Applications that use AbstractBasicAuthHandler, HTTPBasicAuthHandler and ProxyBasicAuthHandler may be affected by this flaw. Other classes may use the vulnerable method http_error_auth_reqed in AbstractBasicAuthHandler as well.
Versions of python36:3.6/python36 as shipped with Red Hat Enterprise Linux 8 are marked as notaffected as they just provide "symlinks" to the main python3 component, which provides the actual interpreter of the Python programming language.
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 | 6.5 | 6.5 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | Required | Required | 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:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Red Hat CVSS v3 Score Explanation
User Interaction set to Required because the client needs to connect to a trusted server and the attack cannot be performed at will by the server.
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.
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