Rapid7 Vulnerability & Exploit Database

Ubuntu: (CVE-2021-4044): openssl vulnerability

Free InsightVM Trial No Credit Card Necessary
2024 Attack Intel Report Latest research by Rapid7 Labs
Back to Search

Ubuntu: (CVE-2021-4044): openssl vulnerability

Severity
5
CVSS
(AV:N/AC:L/Au:N/C:N/I:N/A:P)
Published
12/14/2021
Created
11/21/2024
Added
11/19/2024
Modified
11/19/2024

Description

Internally libssl in OpenSSL calls X509_verify_cert() on the client side to verify a certificate supplied by a server. That function may return a negative return value to indicate an internal error (for example out of memory). Such a negative return value is mishandled by OpenSSL and will cause an IO function (such as SSL_connect() or SSL_do_handshake()) to not indicate success and a subsequent call to SSL_get_error() to return the value SSL_ERROR_WANT_RETRY_VERIFY. This return value is only supposed to be returned by OpenSSL if the application has previously called SSL_CTX_set_cert_verify_callback(). Since most applications do not do this the SSL_ERROR_WANT_RETRY_VERIFY return value from SSL_get_error() will be totally unexpected and applications may not behave correctly as a result. The exact behaviour will depend on the application but it could result in crashes, infinite loops or other similar incorrect responses. This issue is made more serious in combination with a separate bug in OpenSSL 3.0 that will cause X509_verify_cert() to indicate an internal error when processing a certificate chain. This will occur where a certificate does not include the Subject Alternative Name extension but where a Certificate Authority has enforced name constraints. This issue can occur even with valid chains. By combining the two issues an attacker could induce incorrect, application dependent behaviour. Fixed in OpenSSL 3.0.1 (Affected 3.0.0).

Solution(s)

  • ubuntu-upgrade-openssl

insightVM

Advanced vulnerability management analytics and reporting.
Key Features
  • Lightweight Endpoint Agent
  • Live Dashboards
  • Real Risk Prioritization
  • IT-Integrated Remediation Projects
  • Cloud, Virtual, and Container Assessment
  • Integrated Threat Feeds
  • Easy-to-Use RESTful API
  • Automation-Assisted Patching
  • Automated Containment
Free InsightVM Trial View All Features

With Rapid7 live dashboards, I have a clear view of all the assets on my network, which ones can be exploited, and what I need to do in order to reduce the risk in my environment in real-time. No other tool gives us that kind of value and insight.

– Scott Cheney, Manager of Information Security, Sierra View Medical Center

;