Bug 1362190 (CVE-2016-5420) - CVE-2016-5420 curl: Re-using connection with wrong client cert
Summary: CVE-2016-5420 curl: Re-using connection with wrong client cert
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2016-5420
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1363642 1363643 1363644 1364910 1367875
Blocks: 1362200 1395463
TreeView+ depends on / blocked
 
Reported: 2016-08-01 13:32 UTC by Adam Mariš
Modified: 2021-02-17 03:29 UTC (History)
32 users (show)

Fixed In Version: curl 7.50.1
Doc Type: Bug Fix
Doc Text:
It was found that the libcurl library did not check the client certificate when choosing the TLS connection to reuse. An attacker could potentially use this flaw to hijack the authentication of the connection by leveraging a previously created connection with a different client certificate.
Clone Of:
Environment:
Last Closed: 2019-06-08 02:57:07 UTC
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2016:2575 0 normal SHIPPED_LIVE Moderate: curl security, bug fix, and enhancement update 2016-11-03 12:06:39 UTC
Red Hat Product Errata RHSA-2016:2957 0 normal SHIPPED_LIVE Important: Red Hat JBoss Core Services Apache HTTP 2.4.23 Release 2016-12-16 03:11:19 UTC
Red Hat Product Errata RHSA-2018:3558 0 None None None 2018-11-13 08:32:12 UTC

Description Adam Mariš 2016-08-01 13:32:51 UTC 
It was reported that libcurl did not consider client certificates when reusing TLS connections. 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.

External Reference:

https://curl.haxx.se/docs/adv_20160803B.html
Comment 1 Adam Mariš 2016-08-03 09:24:56 UTC 
Created curl tracking bugs for this issue:

Affects: fedora-all [bug 1363642]
Comment 2 Adam Mariš 2016-08-03 09:25:05 UTC 
Created mingw-curl tracking bugs for this issue:

Affects: fedora-all [bug 1363643]
Affects: epel-7 [bug 1363644]
Comment 3 Fedora Update System 2016-08-05 20:52:29 UTC 
curl-7.47.1-6.fc24 has been pushed to the Fedora 24 stable repository. If problems still persist, please make note of it in this bug report.
Comment 5 Fedora Update System 2016-08-16 22:21:05 UTC 
curl-7.43.0-8.fc23 has been pushed to the Fedora 23 stable repository. If problems still persist, please make note of it in this bug report.
Comment 10 errata-xmlrpc 2016-11-03 17:45:10 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2016:2575 https://rhn.redhat.com/errata/RHSA-2016-2575.html
Comment 12 errata-xmlrpc 2016-12-15 22:11:57 UTC 
This issue has been addressed in the following products:



Via RHSA-2016:2957 https://rhn.redhat.com/errata/RHSA-2016-2957.html
Comment 13 errata-xmlrpc 2018-11-13 08:32:01 UTC 
This issue has been addressed in the following products:

  Red Hat Software Collections for Red Hat Enterprise Linux 6
  Red Hat Software Collections for Red Hat Enterprise Linux 7
  Red Hat Software Collections for Red Hat Enterprise Linux 7.4 EUS
  Red Hat Software Collections for Red Hat Enterprise Linux 7.5 EUS
  Red Hat Software Collections for Red Hat Enterprise Linux 7.6 EUS

Via RHSA-2018:3558 https://access.redhat.com/errata/RHSA-2018:3558
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