CVE-2020-25681
HighA heap-based buffer overflow was discovered in the way RRSets are sorted before validating with DNSSEC data.
Published Jan 21, 2021 · Updated Aug 5, 2026 · Also known as ALPINE-CVE-2020-25681, DEBIAN-CVE-2020-25681, DLA-2604-1, DSA-4844-1, SUSE-SU-2021:0162-1, SUSE-SU-2021:0163-1, SUSE-SU-2021:0166-1, SUSE-SU-2021:14604-1, TR-21-0055, UBUNTU-CVE-2020-25681
Key Facts
Patch immediately- CVE-2020-25681 is a high-severity vulnerability (CVSS 8.1 v3.1) affecting Dnsmasq (Thekelleys), Debian Linux, Fedora (Fedoraproject) and 1 more product.
- It is not listed in any known-exploited vulnerabilities catalog. No public exploit code is known.
- EPSS estimates a 81% probability of exploitation in the next 30 days.
- Fixed versions are available, including Dnsmasq 0:2.79-11.el8_2.2, Dnsmasq 2.75-1ubuntu0.16.04.7, Dnsmasq 2.76-17.0.3.el7_9.3.
- Brandefense priority: patch immediately, because it is very likely to be exploited soon.
CVSS v3.1
8.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
81%
Higher than 99.6% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
None known
Get the full CVE-2020-25681 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in the way RRSets are sorted before validating with DNSSEC data. An attacker on the network, who can forge DNS replies such as that they are accepted as valid, could use this flaw to cause a buffer overflow with arbitrary data in a heap memory segment, possibly executing code on the machine. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
Affected Products
109 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| DnsmasqThekelleys | >= dnsmasq 2.83 | 2.83 |
| Debian LinuxDebian | 10.0, 9.0 | n/a |
| FedoraFedoraproject | 32, 33 | n/a |
| dnsmasq-utilsoracle | See advisory | 2.76-17.0.3.el7_9.3 |
Patched Releases
Dnsmasq
0:2.79-11.el8_2.2, 2.75-1ubuntu0.16.04.7, 2.76-17.0.3.el7_9.3, 2.76-5+deb9u3, 2.78-0.16.14.1, 2.78-0.17.15.1, 2.78-18.15.1, 2.78-3.11.1, 2.78-7.6.1, 2.78-lp151.5.6.1, 2.78-lp152.7.3.1, 2.79-13.el8_3.1, 2.79-1ubuntu0.2, 2.80-1.1ubuntu1.2, 2.80-1+deb10u1, 2.82-1.ph1, 2.82-1.ph2, 2.82-1.ph3, 2.83-1, 2.83-r0, 2.85-1, 2.86-1.1, 2.83
dnsmasq-utils
2.76-17.0.3.el7_9.3, 2.78-18.15.1, 2.78-lp151.5.6.1, 2.78-lp152.7.3.1, 2.79-13.el8_3.1, 2.86-1.1
Timeline
Publicly disclosed
Jan 21, 2021
Last updated
Aug 5, 2026
Weakness Type
- CWE-122 Heap-based Buffer Overflow
References
- advisoryhttp://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2021q1/014599.html
- advisoryRHSA-2021:0150
- advisoryRHSA-2021:0151
- advisoryRHSA-2021:0152
- advisoryhttps://access.redhat.com/security/vulnerabilities/RHSB-2021-001
FAQ
Common Questions.
A flaw was found in dnsmasq before version 2.83.
Affected: Dnsmasq (Thekelleys) versions >= dnsmasq 2.83; Debian Linux versions 10.0, 9.0; Fedora (Fedoraproject) versions 32, 33, among others. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including Dnsmasq 0:2.79-11.el8_2.2, Dnsmasq 2.75-1ubuntu0.16.04.7, Dnsmasq 2.76-17.0.3.el7_9.3.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.
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