Security Bulletin
Summary
The urllib3 library 1.26.x before 1.26.4 for Python omits SSL certificate validation in some cases involving HTTPS to HTTPS proxies. The initial connection to the HTTPS proxy (if an SSLContext isn't given via proxy_config) doesn't verify the hostname of the certificate. This means certificates for different servers that still validate properly with the default urllib3 SSLContext will be silently accepted.
Vulnerability Details
CVEID: CVE-2021-33503
DESCRIPTION: urllib3 is vulnerable to a denial of service, caused by a regular expression denial of service (ReDoS) flaw due to catastrophic backtracking. By sending a specially-crafted URL request, a remote attacker could exploit this vulnerability to cause a denial of service condition.
CVSS Base score: 5.3
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/203109 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
CVEID: CVE-2021-28363
DESCRIPTION: urllib3 for python is vulnerable to a man-in-the-middle attack, caused by improper certificate validation in some cases involving HTTPS to HTTPS proxies. An attacker could exploit this vulnerability to launch a man-in-the-middle attack and gain access to the communication channel between endpoints to obtain sensitive information or further compromise the system.
CVSS Base score: 5.9
CVSS Temporal Score: See: https://exchange.xforce.ibmcloud.com/vulnerabilities/198199 for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N)
Affected Products and Versions
| Affected Product(s) | Version(s) |
| Monitor Component | 8.6.2, 8.7 |
Remediation/Fixes
Upgraded to version 8.6.3 or 8.7.1
Workarounds and Mitigations
None
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References
Change History
30 Nov 2021: Initial Publication
*The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Security Bulletin.
Disclaimer
Review the IBM security bulletin disclaimer and definitions regarding your responsibilities for assessing potential impact of security vulnerabilities to your environment.
Document Location
Worldwide
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Document Information
Modified date:
18 March 2022
UID
ibm16564723