# CVE-2020-25683: dnsmasq: A flaw was found in dnsmasq before version 2.83

CVE-2020-25683 is fixed in 4 products on 1 platform, first by dnsmasq 2.79-1ubuntu0.2, released January 18, 2021. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2020-25683
- Priority: High
- CVSS: 7.5 (Medium)
- EPSS: 0.8878
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jan 18, 2021

## Description

A flaw was found in dnsmasq before version 2.83. A heap-based bufferoverflow was discovered in dnsmasq when DNSSEC is enabled and before itvalidates the received DNS entries. A remote attacker, who can create validDNS replies, could use this flaw to cause an overflow in a heap-allocatedmemory. This flaw is caused by the lack of length checks inrfc1035.c:extract_name(), which could be abused to make the code executememcpy() with a negative size in get_rdata() and cause a crash in dnsmasq,resulting in a denial of service. The highest threat from thisvulnerability is to system availability.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | dnsmasq RHEL 8 | 0:2.79-13.el8_3.1 | [RHSA-2021:0150](https://patchblox.com/security/data/fix/linux/rhsa-2021-0150.md) | Jan 19, 2021 |
| Linux | dnsmasq Ubuntu 18.04.6 LTS (bionic) | 2.79-1ubuntu0.2 | [dnsmasq 2.79-1ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-dnsmasq-2.79-1ubuntu0.2.md) | Jan 18, 2021 |
| Linux | dnsmasq Ubuntu 20.04 LTS (focal) | 2.80-1.1ubuntu1.2 | [dnsmasq 2.80-1.1ubuntu1.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-dnsmasq-2.80-1.1ubuntu1.2.md) | Jan 18, 2021 |
| Linux | dnsmasq Ubuntu 24.10 (oracular) | 2.82-1ubuntu2 | [dnsmasq 2.82-1ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-dnsmasq-2.82-1ubuntu2.md) | Jan 19, 2021 |
| Linux | dnsmasq Ubuntu 25.04 (plucky) | 2.82-1ubuntu2 | [dnsmasq 2.82-1ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-dnsmasq-2.82-1ubuntu2.md) | Jan 19, 2021 |
| Linux | dnsmasq ol 8 | 0:2.79-13.el8_3.1 | [ELSA-2021-0150](https://patchblox.com/security/data/fix/linux/elsa-2021-0150.md) | Jan 20, 2021 |
| Linux | dnsmasq-base Ubuntu 18.04.6 LTS (bionic) | 2.79-1ubuntu0.2 | [dnsmasq-base 2.79-1ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-dnsmasq-base-2.79-1ubuntu0.2.md) | Jan 18, 2021 |
| Linux | dnsmasq-base Ubuntu 20.04 LTS (focal) | 2.80-1.1ubuntu1.2 | [dnsmasq-base 2.80-1.1ubuntu1.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-dnsmasq-base-2.80-1.1ubuntu1.2.md) | Jan 18, 2021 |
| Linux | dnsmasq-base Ubuntu 24.10 (oracular) | 2.82-1ubuntu2 | [dnsmasq-base 2.82-1ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-dnsmasq-base-2.82-1ubuntu2.md) | Jan 19, 2021 |
| Linux | dnsmasq-base Ubuntu 25.04 (plucky) | 2.82-1ubuntu2 | [dnsmasq-base 2.82-1ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-dnsmasq-base-2.82-1ubuntu2.md) | Jan 19, 2021 |
| Linux | dnsmasq-base-lua Ubuntu 18.04.6 LTS (bionic) | 2.79-1ubuntu0.2 | [dnsmasq-base-lua 2.79-1ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-dnsmasq-base-lua-2.79-1ubuntu0.2.md) | Jan 18, 2021 |
| Linux | dnsmasq-base-lua Ubuntu 20.04 LTS (focal) | 2.80-1.1ubuntu1.2 | [dnsmasq-base-lua 2.80-1.1ubuntu1.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-dnsmasq-base-lua-2.80-1.1ubuntu1.2.md) | Jan 18, 2021 |
| Linux | dnsmasq-base-lua Ubuntu 24.10 (oracular) | 2.82-1ubuntu2 | [dnsmasq-base-lua 2.82-1ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-dnsmasq-base-lua-2.82-1ubuntu2.md) | Jan 19, 2021 |
| Linux | dnsmasq-base-lua Ubuntu 25.04 (plucky) | 2.82-1ubuntu2 | [dnsmasq-base-lua 2.82-1ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-dnsmasq-base-lua-2.82-1ubuntu2.md) | Jan 19, 2021 |
| Linux | dnsmasq-utils RHEL 8 | 0:2.79-13.el8_3.1 | [RHSA-2021:0150](https://patchblox.com/security/data/fix/linux/rhsa-2021-0150.md) | Jan 19, 2021 |
| Linux | dnsmasq-utils Ubuntu 18.04.6 LTS (bionic) | 2.79-1ubuntu0.2 | [dnsmasq-utils 2.79-1ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-dnsmasq-utils-2.79-1ubuntu0.2.md) | Jan 18, 2021 |
| Linux | dnsmasq-utils Ubuntu 20.04 LTS (focal) | 2.80-1.1ubuntu1.2 | [dnsmasq-utils 2.80-1.1ubuntu1.2](https://patchblox.com/security/data/fix/linux/ubuntu-focal-dnsmasq-utils-2.80-1.1ubuntu1.2.md) | Jan 18, 2021 |
| Linux | dnsmasq-utils Ubuntu 24.10 (oracular) | 2.82-1ubuntu2 | [dnsmasq-utils 2.82-1ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-dnsmasq-utils-2.82-1ubuntu2.md) | Jan 19, 2021 |
| Linux | dnsmasq-utils Ubuntu 25.04 (plucky) | 2.82-1ubuntu2 | [dnsmasq-utils 2.82-1ubuntu2](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-dnsmasq-utils-2.82-1ubuntu2.md) | Jan 19, 2021 |
| Linux | dnsmasq-utils ol 8 | 0:2.79-13.el8_3.1 | [ELSA-2021-0150](https://patchblox.com/security/data/fix/linux/elsa-2021-0150.md) | Jan 20, 2021 |

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