CVE-2019-20444
Description
A HTTP smuggling flaw was found in HttpObjectDecoder.java in Netty in versions prior to version 4.1.44. HTTP headers with an invalid fold, in this case CRLF (carriage return, line feed) without being followed by SP (space) or HTAB (horizontal tab), result in situations where headers can be misread. Data integrity is the highest threat with this vulnerability.
Statement
OpenShift Container Platform ships a vulnerable netty library as part of the logging-elasticsearch5 container. ElasticSearch's security team has stated that the previous vulnerability, CVE-2019-16869, does not pose a substantial practical threat to ElasticSearch 6. We agree that these issues would be difficult to exploit on OpenShift Container Platform so we're reducing the impact of this issue to moderate and may fix it in the future release.
Red Hat Satellite ships a vulnerable version of netty embedded in Candlepin. However, the flaw can not be triggered in that context, because HTTP requests are handled by Tomcat, not by netty. A future release may fix this.
Mitigation
* Use HTTP/2 instead (clear boundaries between requests)
* Disable reuse of backend connections eg.
http-reuse neverin HAProxy or whatever equivalent LB settings
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 | 7.5 | 9.1 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Red Hat CVSS v3 Score Explanation
Red Hat Products do not enable the some conditions required for this flaw, and as such have a base score that differs from NVD's base evaluation, C:H -> C:N, as the degree of confidentiality exposure is purely depending on the back-end web application itself.
Understanding the Weakness (CWE)
Integrity,Non-Repudiation,Access Control
Technical Impact: Unexpected State; Hide Activities; Bypass Protection Mechanism
An attacker could create HTTP messages to exploit a number of weaknesses including 1) the message can trick the web server to associate a URL with another URL's webpage and caching the contents of the webpage (web cache poisoning attack), 2) the message can be structured to bypass the firewall protection mechanisms and gain unauthorized access to a web application, and 3) the message can invoke a script or a page that returns client credentials (similar to a Cross Site Scripting attack).
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