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Bug 1631822 - (CVE-2018-14647) CVE-2018-14647 python: Missing salt initialization in _elementtree.c module
CVE-2018-14647 python: Missing salt initialization in _elementtree.c module
Status: NEW
Product: Security Response
Classification: Other
Component: vulnerability (Show other bugs)
unspecified
All Linux
medium Severity medium
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Assigned To: Red Hat Product Security
impact=moderate,public=20180922,repor...
: Security
Depends On: 1632086 1632088 1632090 1632091 1632092 1632093 1632095 1632096 1632531 1636838 1636839 1636840 1636841 1638355 1632084 1632085 1632087 1632089 1632094 1632097 1632098
Blocks: 1631825
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Reported: 2018-09-21 12:00 EDT by Pedro Sampaio
Modified: 2018-10-25 19:13 EDT (History)
24 users (show)

See Also:
Fixed In Version: python 3.7.1, python 3.6.7, python 2.7.16
Doc Type: If docs needed, set a value
Doc Text:
Python's elementtree C accelerator failed to initialise Expat's hash salt during initialization. This could make it easy to conduct denial of service attacks against Expat by contructing an XML document that would cause pathological hash collisions in Expat's internal data structures, consuming large amounts CPU and RAM.
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RHEL 7.3 requirements from Atomic Host:
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Description Pedro Sampaio 2018-09-21 12:00:27 EDT 
A flaw was found in python's _elementtree.c module, a wrapper for libexpat XML parser. xml.etree C accelerator don't call XML_SetHashSalt(), failing to properly initiate the random hash seed from a good CSPRNG source and making hash collision attacks with carefully crafted XML data easier.

Upstream bug:

https://bugs.python.org/issue34623.
Comment 1 Pedro Sampaio 2018-09-21 12:01:58 EDT 
Acknowledgments:

Name: the Python Security Response Team
Comment 2 Doran Moppert 2018-09-24 01:51:35 EDT 
Note that expat >=2.2.2 will internally initialize the hash salt with a more securely generated value providing arc4random, getrandom or /dev/urandom is available. The risk is greatest on earlier versions of expat (eg 2.1.0) or where such sources are not available.
Comment 3 Doran Moppert 2018-09-24 01:51:54 EDT 
External References:

https://bugs.python.org/issue34623
Comment 4 Doran Moppert 2018-09-24 01:54:41 EDT 
Created python2 tracking bugs for this issue:

Affects: fedora-all [bug 1632089]


Created python26 tracking bugs for this issue:

Affects: fedora-all [bug 1632084]


Created python3 tracking bugs for this issue:

Affects: fedora-all [bug 1632085]


Created python33 tracking bugs for this issue:

Affects: fedora-all [bug 1632088]


Created python34 tracking bugs for this issue:

Affects: epel-6 [bug 1632091]
Affects: epel-7 [bug 1632092]
Affects: fedora-all [bug 1632086]


Created python35 tracking bugs for this issue:

Affects: fedora-all [bug 1632087]


Created python36 tracking bugs for this issue:

Affects: epel-7 [bug 1632093]


Created python37 tracking bugs for this issue:

Affects: fedora-all [bug 1632090]
Comment 6 Doran Moppert 2018-09-24 02:05:30 EDT 
Expat's low-quality hash initialization as known as CVE-2016-5300:

https://bugzilla.redhat.com/show_bug.cgi?id=1343085
https://github.com/libexpat/libexpat/pull/30/commits
Comment 7 Miro Hrončok 2018-09-24 06:06:32 EDT 
I miss python36 fedora-all bugzilla.
Comment 8 Doran Moppert 2018-09-24 22:38:03 EDT 
Created python36 tracking bugs for this issue:

Affects: fedora-all [bug 1632531]
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