# CVE-2021-41687: dcmtk: DCMTK through 3.6.6 does not handle memory free properly

CVE-2021-41687 is fixed in 4 products on 1 platform, first by dcmtk 3.6.2-3ubuntu0.1~esm3, released June 28, 2022. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-41687
- Priority: High
- CVSS: 7.5 (Low)
- EPSS: 0.0184
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 28, 2022

## Description

DCMTK through 3.6.6 does not handle memory free properly. The program malloc a heap memory for parsing data, but does not free it when error in parsing. Sending specific requests to the dcmqrdb program incur the memory leak. An attacker can use it to launch a DoS attack.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | dcmtk Debian 11.6 (bullseye) | 3.6.5-1+deb11u1 | [DLA-4038-1](https://patchblox.com/security/data/fix/linux/dla-4038-1.md) | Jan 31, 2025 |
| Linux | dcmtk Debian 12.15 (bookworm) | 3.6.7-1 | [DEBIAN-CVE-2021-41687](https://patchblox.com/security/data/fix/linux/debian-cve-2021-41687.md) | Jun 28, 2022 |
| Linux | dcmtk Debian 13.5 (trixie) | 3.6.7-1 | [DEBIAN-CVE-2021-41687](https://patchblox.com/security/data/fix/linux/debian-cve-2021-41687.md) | Jun 28, 2022 |
| Linux | dcmtk Debian 14 | 3.6.7-1 | [DEBIAN-CVE-2021-41687](https://patchblox.com/security/data/fix/linux/debian-cve-2021-41687.md) | Jun 28, 2022 |
| Linux | dcmtk Ubuntu 18.04.6 LTS (bionic) | 3.6.2-3ubuntu0.1~esm3 | [dcmtk 3.6.2-3ubuntu0.1~esm3](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-dcmtk-3.6.2-3ubuntu0.1-esm3.md) | Jun 28, 2022 |
| Linux | dcmtk Ubuntu 20.04 LTS (focal) | 3.6.4-2.1ubuntu0.1~esm1 | [dcmtk 3.6.4-2.1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-dcmtk-3.6.4-2.1ubuntu0.1-esm1.md) | Dec 2, 2022 |
| Linux | dcmtk Ubuntu 22.04.1 LTS (jammy) | 3.6.6-5ubuntu0.1~esm1 | [dcmtk 3.6.6-5ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-dcmtk-3.6.6-5ubuntu0.1-esm1.md) | Dec 2, 2022 |
| Linux | libdcmtk12 Ubuntu 18.04.6 LTS (bionic) | 3.6.2-3ubuntu0.1~esm3 | [libdcmtk12 3.6.2-3ubuntu0.1~esm3](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libdcmtk12-3.6.2-3ubuntu0.1-esm3.md) | Jun 28, 2022 |
| Linux | libdcmtk14 Ubuntu 20.04 LTS (focal) | 3.6.4-2.1ubuntu0.1~esm1 | [libdcmtk14 3.6.4-2.1ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libdcmtk14-3.6.4-2.1ubuntu0.1-esm1.md) | Dec 2, 2022 |
| Linux | libdcmtk16 Ubuntu 22.04.1 LTS (jammy) | 3.6.6-5ubuntu0.1~esm1 | [libdcmtk16 3.6.6-5ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libdcmtk16-3.6.6-5ubuntu0.1-esm1.md) | Dec 2, 2022 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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