CVE-2020-25682

HIGH EPSS 99.3%
Published Jan 20, 20215y ago · Modified Jun 17, 20262w ago
8.1 CVSS 3.1
High
Find Similar
Published Jan 20, 2021 5y ago
Last Modified Jun 17, 2026 2w ago

Description

A flaw was found in dnsmasq before 2.83. A buffer overflow vulnerability was discovered in the way dnsmasq extract names from DNS packets before validating them with DNSSEC data. An attacker on the network, 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 the 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. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

CVSS Details

Base Score
8.1
Exploitability
2.2
Impact
5.9
Vector string
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector Network
Attack Complexity High
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
99.3% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 2

CWE-122
CWE-787 Out-of-bounds Write Memory Safety

Affected Products 5

VendorProductVersionRange
thekelleysdnsmasq* <2.83
fedoraprojectfedora32any
fedoraprojectfedora33any
debiandebian_linux9.0any
debiandebian_linux10.0any

References 8

  • bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=1882014
    Issue TrackingPatchThird Party Advisory
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2021/03/msg00027.html
    Mailing ListThird Party Advisory
  • lists.fedoraproject.org https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/
  • lists.fedoraproject.org https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/
  • security.gentoo.org https://security.gentoo.org/glsa/202101-17
    Third Party Advisory
  • debian.org https://www.debian.org/security/2021/dsa-4844
    Third Party Advisory
  • jsof-tech.com https://www.jsof-tech.com/disclosures/dnspooq/
    Third Party Advisory
  • kb.cert.org https://www.kb.cert.org/vuls/id/434904

Remediation

  • bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=1882014
    Issue TrackingPatchThird Party Advisory