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[Dovecot-news] CVE-2019-11500:

Dear subscribers, we have been made aware of critical vulnerability in Dovecot and Pigeonhole.


Open-Xchange Security Advisory 2019-08-14

Product: Dovecot
Vendor: OX Software GmbH

Internal reference: DOV-3278
Vulnerability type: Improper input validation (CWE-20)
Vulnerable version: All versions prior to 2.3.7.2 and 2.2.36.4
Vulnerable component: IMAP and ManageSieve protocol parsers (before and after login)
Report confidence: Confirmed
Solution status: Fixed by Vendor
Fixed version: 2.3.7.2, 2.2.36.4
Researcher credits: Nick Roessler and Rafi Rubin, University of Pennsylvania
Vendor notification: 2019-04-13
Solution date: 2019-06-05
Public disclosure: 2019-08-28
CVE reference: CVE-2019-11500
CVSS: 8.1 (CVSS3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H)

Vulnerability Details:

IMAP and ManageSieve protocol parsers do not properly handle NUL byte when scanning data in quoted strings, leading to out of bounds heap memory writes.

Risk:

This vulnerability allows for out-of-bounds writes to objects stored on the heap up to 8096 bytes in pre-login phase, and 65536 bytes post-login phase, allowing a sufficiently skilled attacker to perform complicated attacks that can lead to leaking private information or remote code execution. Abuse of this bug is very difficult to observe, as it does not necessarily cause a crash. Attempts to abuse this bug are not directly evident from logs.

Steps to reproduce:

This bug is best observed using valgrind to see the out of bounds read with following snippet:

perl -e ‘print “a id (“foo” “”.(“x"x1021).”\A” “bar”"\000".(“x"x1020).”\A")\n"’ | nc localhost 143

Solution:

Operators should update to the latest Patch Release. There is no workaround for the issue.


Aki Tuomi

Open-Xchange oy


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