Bug 1999190 (CVE-2021-39272) - CVE-2021-39272 fetchmail: STARTTLS session encryption bypassing
Summary: CVE-2021-39272 fetchmail: STARTTLS session encryption bypassing
Keywords:
Status: NEW
Alias: CVE-2021-39272
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1999275 1999276 1999191
Blocks: 1999192
TreeView+ depends on / blocked
 
Reported: 2021-08-30 16:46 UTC by Guilherme de Almeida Suckevicz
Modified: 2021-08-31 06:36 UTC (History)
2 users (show)

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Description Guilherme de Almeida Suckevicz 2021-08-30 16:46:57 UTC
Fetchmail before 6.4.22 fails to enforce STARTTLS session encryption in some circumstances, such as a certain situation with IMAP and PREAUTH.

References:
https://www.fetchmail.info/fetchmail-SA-2021-02.txt
http://www.openwall.com/lists/oss-security/2021/08/27/3
https://www.fetchmail.info/security.html

Comment 1 Guilherme de Almeida Suckevicz 2021-08-30 16:47:12 UTC
Created fetchmail tracking bugs for this issue:

Affects: fedora-all [bug 1999191]

Comment 3 Garrett Tucker 2021-08-30 19:06:47 UTC
This specific flaw is caused by a myriad of factors that result in the possibility of communications being sent in clear text. Due to how IMAP and fetchmail work, it was possible for fetchmail to start communications in clear text and then try to upgrade the communication to an encrypted communication (STARTTLS protocol). However, IMAP in "Pre Auth" mode does not allow for the communications to be started via STARTTLS. Thus if a user used IMAP, the server used Pre Auth, TLS was forced and no ssl mode was configured, the communications would be sent entirely in clear text. This has been solved in Fetchmail 6.4.22 or above.


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