CVE-2020-25682: Buffer Overflow
First published: Wed Sep 23 2020(Updated: )
A buffer overflow vulnerability was discovered in the way dnsmasq extract names from DNS packets before validating them with DNSSEC data. An attacker, who can create valid DNS replies, could use this flaw to cause an overflow with arbitrary data in a heap-allocated memory, possibly executing code on the machine. The flaw is in rfc1035.c:extract_name() function, which writes data to the memory pointed by `name` assuming MAXDNAME*2 bytes are available in the buffer. However, in some code execution paths it is possible extract_name() gets passed an offset from the base buffer, thus reducing in practice the number of available bytes that can be written in the buffer.
Credit: secalert@redhat.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| redhat/dnsmasq | <2.83 | 2.83 |
| Thekelleys Dnsmasq | <2.83 | |
| Fedoraproject Fedora | =32 | |
| Fedoraproject Fedora | =33 | |
| Debian Debian Linux | =9.0 | |
| Debian Debian Linux | =10.0 | |
| debian/dnsmasq | 2.80-1+deb10u1 2.85-1 2.89-1 |
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Reference Links
- https://bugzilla.redhat.com/show_bug.cgi?id=1882014
- https://lists.debian.org/debian-lts-announce/2021/03/msg00027.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/
- https://security.gentoo.org/glsa/202101-17
- https://www.debian.org/security/2021/dsa-4844
- https://www.jsof-tech.com/disclosures/dnspooq/
- https://www.openwall.com/lists/oss-security/2021/01/19/1
- https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=4e96a4be685c9e4445f6ee79ad0b36b9119b502a
- https://security-tracker.debian.org/tracker/CVE-2020-25682
- https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1917782
- https://access.redhat.com/errata/RHSA-2021:0152
- https://access.redhat.com/errata/RHSA-2021:0150
- http://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=4e96a4be685c9e4445f6ee79ad0b36b9119b502a
- https://access.redhat.com/errata/RHSA-2021:0151
- https://access.redhat.com/security/cve/cve-2020-25682
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/
Frequently Asked Questions
What is CVE-2020-25682?
CVE-2020-25682 is a buffer overflow vulnerability in dnsmasq before version 2.83.
How does CVE-2020-25682 affect dnsmasq?
CVE-2020-25682 allows an attacker on the network to cause a buffer overflow in dnsmasq by creating valid DNS replies with arbitrary data.
What is the severity of CVE-2020-25682?
CVE-2020-25682 has a severity score of 8.1 (high).
Which software versions are affected by CVE-2020-25682?
CVE-2020-25682 affects dnsmasq versions before 2.83.
How can I fix CVE-2020-25682?
To fix CVE-2020-25682, update dnsmasq to version 2.83 or higher.
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