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CVE Record

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

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.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

BigBlueButton servers in affected versions can be knocked offline through a malformed User-Agent header hitting the html5client/useragent path. The issue affects availability, not data confidentiality or integrity, but it can disrupt meetings and dependent services.

Executive priority

Prioritize remediation for public BigBlueButton deployments because the vulnerability can disrupt conferencing without authentication. Treat this as an availability risk requiring prompt upgrade or vendor-documented routing mitigation.

Technical view

The vulnerability is a regular expression denial of service in bbb-html5. The useragent library parses the User-Agent header through useragent.lookup(), where crafted input referencing SmartWatch handling can trigger expensive regex behavior. Fixed releases remove the html5client/useragent handler.

Likely exposure

Exposure is likely where BigBlueButton 2.2 through before 2.3.19, 2.4.0 through before 2.4.7, or 2.5 alpha before 2.5.0-beta.2 is internet-accessible and Nginx forwards requests to html5client/useragent.

Exploitation context

The source bundle does not show KEV listing or cited evidence of active exploitation. The CVSS vector indicates unauthenticated network reachability, low attack complexity, and high availability impact.

Researcher notes

Evidence supports a ReDoS in User-Agent parsing, fixed by removing the endpoint in listed releases. The bundle names CWE-20 and CVSS 7.5. It does not provide evidence of data exposure, integrity impact, or confirmed exploitation.

Mitigation direction

  • Upgrade BigBlueButton to 2.3.19, 2.4.7, 2.5.0-beta.2, or a later fixed release.
  • If upgrade is delayed, disable Nginx forwarding to html5client/useragent per the GitHub advisory.
  • Check vendor guidance before applying any alternative workaround.
  • Monitor bbb-html5 resource usage and availability during remediation.

Validation and detection

  • Inventory BigBlueButton servers and identify versions in the affected ranges.
  • Confirm the html5client/useragent route is absent or blocked after remediation.
  • Review Nginx configuration for forwarding rules to the vulnerable handler.
  • Review bbb-html5 availability metrics for unexplained CPU saturation or service failures.
Prepared
Confidence
high
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-20: Exact CWE lookup

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Open ATT&CK lookup
cve · low confidence lookup

CVE-2022-29169 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
4Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2022-29169Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
bigbluebuttonbigbluebutton>= 2.2, < 2.3.19, >= 2.4.0, < 2.4.7, >= 2.5-alpha-1, < 2.5.0-beta.2Listed
Weakness

CWE details

CWE-20

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-20 · source CWE mapping

Improper Input Validation

Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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