Bug 1471970 - (CVE-2017-9951) CVE-2017-9951 memcached: Heap-based buffer over-read in try_read_command function (incomplete fix for CVE-2016-8705)
CVE-2017-9951 memcached: Heap-based buffer over-read in try_read_command func...
Status: CLOSED ERRATA
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
unspecified
All Linux
low Severity low
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Assigned To: Red Hat Product Security
impact=low,public=20170717,reported=2...
: Security
Depends On: 1594877 1471972 1485737
Blocks: 1485738
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Reported: 2017-07-17 15:54 EDT by Pedro Sampaio
Modified: 2018-06-27 04:04 EDT (History)
29 users (show)

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Last Closed: 2017-12-06 23:53:44 EST
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Description Pedro Sampaio 2017-07-17 15:54:19 EDT
The try_read_command function in memcached.c in memcached before 1.4.39 allows remote attackers to cause a denial of service (segmentation fault) via a request to add/set a key, which makes a comparison between signed and unsigned int and triggers a heap-based buffer over-read. NOTE: this vulnerability exists because of an incomplete fix for CVE-2016-8705. 

References:

https://www.twistlock.com/2017/07/13/cve-2017-9951-heap-overflow-memcached-server-1-4-38-twistlock-vulnerability-report/
https://github.com/memcached/memcached/wiki/ReleaseNotes1439
https://groups.google.com/forum/message/raw?msg=memcached/ubGWrkmrr4E/nrm1SeVJAQAJ
Comment 1 Pedro Sampaio 2017-07-17 15:57:04 EDT
Created memcached tracking bugs for this issue:

Affects: fedora-all [bug 1471972]
Comment 2 Jon Schlueter 2017-08-24 14:20:57 EDT
RDO has memcached-1.4.39-1.el7 which includes fix for this CVE according to change log.
Comment 7 Doran Moppert 2017-08-27 23:45:49 EDT
Mitigation:

This flaw is in the memcached binary protocol. If your client programs only use the ASCII protocol when communicating with memcached, you can disable the binary protocol and protect against this flaw by adding "-B ascii" to OPTIONS in /etc/sysconfig/memcached.
Comment 8 Joshua Padman 2017-12-07 00:09:18 EST
Statement:

Red Hat Product Security has rated this issue as having Low security impact. This issue is not currently planned to be addressed in future updates. For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/classification/.

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