# CVE-2020-25682: dnsmasq: A flaw was found in dnsmasq before 2.83

CVE-2020-25682 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-2020-25682
- Priority: High
- CVSS: 8.1 (Medium)
- EPSS: 0.7507
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jan 18, 2021

## Description

A flaw was found in dnsmasq before 2.83. A buffer overflow vulnerabilitywas discovered in the way dnsmasq extract names from DNS packets beforevalidating them with DNSSEC data. An attacker on the network, who cancreate valid DNS replies, could use this flaw to cause an overflow witharbitrary data in a heap-allocated memory, possibly executing code on themachine. The flaw is in the rfc1035.c:extract_name() function, which writesdata to the memory pointed by name assuming MAXDNAME*2 bytes are availablein the buffer. However, in some code execution paths, it is possibleextract_name() gets passed an offset from the base buffer, thus reducing,in practice, the number of available bytes that can be written in thebuffer. The highest threat from this vulnerability is to dataconfidentiality and integrity as well as 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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