CVE-2016-5420

curl and libcurl before 7.50.1 do not check the client certificate when choosing the TLS connection to reuse, which might allow remote attackers to hijack the authentication of the connection by leveraging a previously created connection with a different client certificate.

Weakness

The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action.

Affected Software

Name	Vendor	Start Version	End Version
Debian_linux	Debian	8.0 (including)	8.0 (including)
Red Hat Enterprise Linux 7	RedHat	curl-0:7.29.0-35.el7	*
Red Hat Software Collections for Red Hat Enterprise Linux 6	RedHat	httpd24-curl-0:7.61.1-1.el6	*
Red Hat Software Collections for Red Hat Enterprise Linux 6	RedHat	httpd24-httpd-0:2.4.34-7.el6	*
Red Hat Software Collections for Red Hat Enterprise Linux 6	RedHat	httpd24-nghttp2-0:1.7.1-7.el6	*
Red Hat Software Collections for Red Hat Enterprise Linux 7	RedHat	httpd24-curl-0:7.61.1-1.el7	*
Red Hat Software Collections for Red Hat Enterprise Linux 7	RedHat	httpd24-httpd-0:2.4.34-7.el7	*
Red Hat Software Collections for Red Hat Enterprise Linux 7	RedHat	httpd24-nghttp2-0:1.7.1-7.el7	*
Red Hat Software Collections for Red Hat Enterprise Linux 7.4 EUS	RedHat	httpd24-curl-0:7.61.1-1.el7	*
Red Hat Software Collections for Red Hat Enterprise Linux 7.4 EUS	RedHat	httpd24-httpd-0:2.4.34-7.el7	*
Red Hat Software Collections for Red Hat Enterprise Linux 7.4 EUS	RedHat	httpd24-nghttp2-0:1.7.1-7.el7	*
Red Hat Software Collections for Red Hat Enterprise Linux 7.5 EUS	RedHat	httpd24-curl-0:7.61.1-1.el7	*
Red Hat Software Collections for Red Hat Enterprise Linux 7.5 EUS	RedHat	httpd24-httpd-0:2.4.34-7.el7	*
Red Hat Software Collections for Red Hat Enterprise Linux 7.5 EUS	RedHat	httpd24-nghttp2-0:1.7.1-7.el7	*
Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUS	RedHat	httpd24-curl-0:7.61.1-1.el7	*
Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUS	RedHat	httpd24-httpd-0:2.4.34-7.el7	*
Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUS	RedHat	httpd24-nghttp2-0:1.7.1-7.el7	*
Text-Only JBCS	RedHat		*
Curl	Ubuntu	esm-infra-legacy/trusty	*
Curl	Ubuntu	esm-infra/xenial	*
Curl	Ubuntu	precise	*
Curl	Ubuntu	trusty	*
Curl	Ubuntu	trusty/esm	*
Curl	Ubuntu	upstream	*
Curl	Ubuntu	vivid/stable-phone-overlay	*
Curl	Ubuntu	vivid/ubuntu-core	*
Curl	Ubuntu	xenial	*

Potential Mitigations

Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) to enforce the roles at the appropriate boundaries.
Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page.
One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.

NVD	https://nvd.nist.gov/vuln/detail/CVE-2016-5420
CWE	https://cwe.mitre.org/data/definitions/285.html

Improper Authorization

Weakness

Affected Software

Potential Mitigations

References

CVE-2016-5420

Improper Authorization

Weakness

Affected Software

Potential Mitigations

Related Attack Patterns

References