CVE-2017-7468
Published: 19 April 2017
In curl and libcurl 7.52.0 to and including 7.53.1, libcurl would attempt to resume a TLS session even if the client certificate had changed. That is unacceptable since a server by specification is allowed to skip the client certificate check on resume, and may instead use the old identity which was established by the previous certificate (or no certificate). libcurl supports by default the use of TLS session id/ticket to resume previous TLS sessions to speed up subsequent TLS handshakes. They are used when for any reason an existing TLS connection couldn't be kept alive to make the next handshake faster. This flaw is a regression and identical to CVE-2016-5419 reported on August 3rd 2016, but affecting a different version range.
From the Ubuntu Security Team
It was discovered that curl incorrectly handled client certificates when resuming a TLS session. A remote attacker could use this to hijack a previously authenticated connection.
Notes
| Author | Note |
|---|---|
| sbeattie | reported upstream mitigation: Set `CURLOPT_SSL_SESSIONID_CACHE` to 0L when using client certificates |
Priority
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 7.5 |
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | None |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | None |
| Integrity impact | High |
| Availability impact | None |
| Vector | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |