Bug 1495415 (CVE-2017-14495) - CVE-2017-14495 dnsmasq: memory exhaustion vulnerability in the EDNS0 code
Summary: CVE-2017-14495 dnsmasq: memory exhaustion vulnerability in the EDNS0 code
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2017-14495
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1495516 1495517 1497691
Blocks: 1495418
TreeView+ depends on / blocked
 
Reported: 2017-09-26 02:00 UTC by Fabio Olive Leite
Modified: 2021-02-17 01:28 UTC (History)
24 users (show)

Fixed In Version: dnsmasq 2.78
Doc Type: If docs needed, set a value
Doc Text:
A memory exhaustion flaw was found in dnsmasq in the EDNS0 code. An attacker could send crafted DNS packets which would trigger memory allocations which would never be freed, leading to unbounded memory consumption and eventually a crash. This issue only affected configurations using one of the options: add-mac, add-cpe-id, or add-subnet.
Clone Of:
Environment:
Last Closed: 2017-10-02 18:15:29 UTC
Embargoed:

Attachments (Terms of Use)
Upstream commit (2.02 KB, patch)
2017-09-26 10:47 UTC, Tomas Hoger 		no flags Details | Diff
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Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2017:2836 0 normal SHIPPED_LIVE Critical: dnsmasq security update 2017-10-02 21:18:46 UTC

Description Fabio Olive Leite 2017-09-26 02:00:42 UTC 
Red Hat Product Security has been made aware of an Denial of Service vulnerability affecting the DNS implementation of dnsmasq.
Comment 1 Doran Moppert 2017-09-26 05:12:11 UTC 
Acknowledgments:

Name: Felix Wilhelm (Google Security Team), Fermin J. Serna (Google Security Team), Gabriel Campana (Google Security Team), Kevin Hamacher (Google Security Team), Ron Bowes (Google Security Team)
Comment 2 Doran Moppert 2017-09-26 08:40:06 UTC 
Versions of dnsmasq shipped with Red Hat Enterprise Linux 6 and 5 do not include the EDNS0 code which includes this flaw.
Comment 3 Tomas Hoger 2017-09-26 08:48:54 UTC 
Further details from the 2.78 pre-release CHANGELOG:

    Fix out-of-memory Dos vulnerability. An attacker which can
    send malicious DNS queries to dnsmasq can trigger memory
    allocations in the add_pseudoheader function
    The allocated memory is never freed which leads to a DoS
    through memory exhaustion. dnsmasq is vulnerable only
    if one of the following option is specified:
    --add-mac, --add-cpe-id or --add-subnet.
    CVE-2017-14495 applies.
    Credit to Felix Wilhelm, Fermin J. Serna, Gabriel Campana
    and Kevin Hamacher of the Google Security Team for
    finding this.
Comment 5 Tomas Hoger 2017-09-26 10:47:54 UTC 
Created attachment 1330994 [details]
Upstream commit
Comment 6 Tomas Hoger 2017-09-26 19:59:58 UTC 
Relevant memory allocation that was not freed properly was added in this commit:

http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commitdiff;h=5bb88f096363e66ac08e31761f850a1d5aa22244

The first upstream version including this change is 2.76.
Comment 8 Adam Mariš 2017-10-02 13:14:33 UTC 
External References:

https://access.redhat.com/security/vulnerabilities/3199382
https://security.googleblog.com/2017/10/behind-masq-yet-more-dns-and-dhcp.html
Comment 9 Adam Mariš 2017-10-02 13:19:02 UTC 
Created dnsmasq tracking bugs for this issue:

Affects: fedora-all [bug 1497691]
Comment 10 Tomas Hoger 2017-10-02 13:44:36 UTC 
Upstream commit:

http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commitdiff;h=51eadb692a5123b9838e5a68ecace3ac579a3a45

Google Security Team's repository with test cases:

https://github.com/google/security-research-pocs/tree/master/vulnerabilities/dnsmasq
Comment 11 errata-xmlrpc 2017-10-02 17:21:04 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2017:2836 https://access.redhat.com/errata/RHSA-2017:2836
Comment 12 Garth Mollett 2017-10-03 20:59:04 UTC 
Statement:

Red Hat OpenStack Platform includes the dnsmasq-utils RPM which does not contain this flaw's affected code-paths; Red Hat OpenStack Platform is therefore listed as not affected.

However, because all versions of Red Hat OpenStack Platform are based on Red Hat Enterprise Linux, all Red Hat OpenStack Platform users should absolutely upgrade the dnsmasq RPM from Red Hat Enterprise Linux as a matter of urgency using standard update mechanisms (such as 'yum update' or 'openstack overcloud update').
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