Buffer overflow in Thekelleys Dnsmasq
CVE-2020-25687
A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in dnsmasq when DNSSEC is enabled and before it validates the received DNS entries. This flaw allows a remote attacker, who can create valid DNS replies, to cause an overflow in a heap-allocated memory. This flaw is caused by the lack of length checks in rfc1035.c:extract_name(), which could be abused to make the code execute memcpy() with a negative size in sort_rrset() and cause a crash in dnsmasq, resulting in a denial of service. The highest threat from this vulnerability is to system availability.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.893 (99.8th percentile), scored .
High probability of exploitation in the next 30 days — patch promptly. 100th percentile — 99.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.867 · newest: 0.893 · change: +0.026
Affected products
- Thekelleys Dnsmasq
- Debian Linux — versions 9.0, 10.0
- Fedoraproject Fedora — versions 32, 33
- Dnsmasq — versions dnsmasq 2.83
Weakness classification (CWE)
Public proof-of-concept exploits
References
- www.jsof-tech.com/disclosures/dnspooq/ (Third Party Advisory)
- bugzilla.redhat.com/show_bug.cgi (Patch, Third Party Advisory, Issue Tracking)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- security.gentoo.org/glsa/202101-17 (vendor-advisory, Third Party Advisory)
- www.debian.org/security/2021/dsa-4844 (vendor-advisory, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- lists.debian.org/debian-lts-announce/2021/03/msg00027.html (mailing-list, Mailing List, Third Party Advisory)
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2020-25687?
- CVE-2020-25687 is a medium-severity vulnerability in Thekelleys Dnsmasq, classified under Heap-based Buffer Overflow. CVSS score: 5.9/10. Published 2021-01-20.
- How severe is CVE-2020-25687?
- Medium severity. CVSS v3 base score is 5.9 out of 10.
- Is CVE-2020-25687 known to be exploited?
- 6 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.