---
title: "CVE-2020-25683: Heap-based Buffer Overflow | CubePath"
description: "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…"
language: en
source: https://cubepath.com/security/cve/CVE-2020-25683
---

# CVE-2020-25683: Heap-based Buffer Overflow | CubePath

## Description

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. A remote attacker, who can create valid DNS replies, could use this flaw 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 get\_rdata() and cause a crash in dnsmasq, resulting in a denial of service. The highest threat from this vulnerability is to system availability.

Official description from the CVE record, published by redhat. Copyright © 1999-2026 The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CVE license. [View the record on cve.org](https://www.cve.org/CVERecord?id=CVE-2020-25683)

## Key data

### EPSS

Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days.

Score

0.88775 (88.8% probability)

Percentile

99.8%

Scores of

Nov 10, 2026

Model

v2026.06.15

### Weakness (CWE)

CWE catalog version 5.0.

CWE names: Copyright © 2006-2026, The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CWE license.

- [CWE-122](https://cwe.mitre.org/data/definitions/122.html) Heap-based Buffer Overflow

## Affected products

Products listed in the CVE record, as the CNA published them.

- dnsmasq

  - affected: dnsmasq 2.83

## References

Links listed in the CVE record. They lead to other sites, which CubePath does not control.

- [jsof-tech.com/disclosures/dnspooq](https://www.jsof-tech.com/disclosures/dnspooq/)
- [bugzilla.redhat.com/show\_bug.cgi?id=1882018](https://bugzilla.redhat.com/show%5Fbug.cgi?id=1882018)
- [FEDORA-2021-84440e87ba](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WYW3IR6APUSKOYKL5FT3ACTIHWHGQY32/)  (lists.fedoraproject.org) vendor-advisory
- [GLSA-202101-17](https://security.gentoo.org/glsa/202101-17)  (security.gentoo.org) vendor-advisory
- [DSA-4844](https://www.debian.org/security/2021/dsa-4844)  (debian.org) vendor-advisory
- [FEDORA-2021-2e4c3d5a9d](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/)  (lists.fedoraproject.org) vendor-advisory
- [\[debian-lts-announce\] 20210322 \[SECURITY\] \[DLA 2604-1\] dnsmasq security update](https://lists.debian.org/debian-lts-announce/2021/03/msg00027.html)  (lists.debian.org) mailing-list
- [kb.cert.org/vuls/id/434904](https://www.kb.cert.org/vuls/id/434904)

## Timeline

1. ID reserved Sep 16, 2020
2. Record published Jan 20, 2021
3. Record last updated Nov 4, 2025

## Look up another CVE

## About CubePath

CubePath is a cloud provider with data centers in Europe and the United States. It offers VPS, bare metal servers and DDoS protection.

[Cloud VPS](https://cubepath.com/vps) [DDoS protection](https://cubepath.com/ddos-protection)

Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 20:02 UTC. [Sources and licenses](https://cubepath.com/security/cve/legal)