Bug 1477529 (CVE-2017-12132)

Summary: CVE-2017-12132 glibc: Fragmentation attacks possible when EDNS0 is enabled
Product: [Other] Security Response Reporter: Adam Mariš <amaris>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: arjun.is, ashankar, codonell, dj, fweimer, glibc-bugzilla, law, mfabian, mnewsome, pfrankli, sardella, siddhesh, slawomir, srikar.betarapalli
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: glibc 2.26 Doc Type: If docs needed, set a value
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Clone Of: Environment:
Last Closed: 2019-06-08 03:19:47 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1477530, 1487063    
Bug Blocks: 1477532    

Description Adam Mariš 2017-08-02 10:56:00 UTC 
The DNS stub resolver in the GNU C Library (aka glibc or libc6) before version 2.26, when EDNS support is enabled, will solicit large UDP responses from name servers, potentially simplifying off-path DNS spoofing attacks due to IP fragmentation.

Upstream bug:

https://sourceware.org/bugzilla/show_bug.cgi?id=21361
Comment 1 Adam Mariš 2017-08-02 10:56:32 UTC 
Created glibc tracking bugs for this issue:

Affects: fedora-all [bug 1477530]
Comment 3 Huzaifa S. Sidhpurwala 2017-08-31 09:20:11 UTC 
Statement:

This issue only affects systems which use a remote recursive resolver and enable EDNS0, either with the “edns0” option in /etc/resolv.conf, or using the RES_USE_EDNS0 or RES_USE_DNSSEC resolver flags. The underlying issue affects recursive resolvers such as BIND and Unbound as well, and has to be fixed separately there.
Comment 4 errata-xmlrpc 2018-04-10 08:21:05 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2018:0805 https://access.redhat.com/errata/RHSA-2018:0805