Vulnerability identifier: #VU378
Vulnerability risk: Medium
CVSSv3.1: 5.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N/E:U/RL:O/RC:C]
CVE-ID:
CWE-ID:
CWE-285
Exploitation vector: Network
Exploit availability: No
Vulnerable software:
cURL
Client/Desktop applications /
Other client software
Vendor: curl.haxx.se
Description
The vulnerability allows a remote attacker to gain access to sensitive information.
The vulnerability exists due to an error when handling client TLS certificates during connection reuse. libcurl supports reuse of established connections for subsequent requests. It does this by keeping a few previous connections "alive" in a connection pool so that a subsequent request that can use one of them instead of creating a new connection will do so.
When using a client certificate for a connection that was then put into the connection pool, that connection could then wrongly get reused in a subsequent request to that same server that either didn't use a client certificate at all or that asked to use a different client certificate thus trying to tell the user that it is a different entity.
This mistakenly using the wrong connection could of course lead to applications sending requests to the wrong realms of the server using authentication that it wasn't supposed to have for those operations.
Mitigation
Install update from vendor's website.
Vulnerable software versions
cURL: 7.7 - 7.50.0
External links
http://curl.se/docs/CVE-2016-5420.html
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.