CVE-2021-29399Network attack vector

Cross-site scripting via inadequately filtered BBCode

Published Apr 19, 2021 · Updated Aug 3, 2024

Cross-site scripting in XMB allows remote attackers to run browser scripts through crafted BBCode input viewed by other users. The BBCode processor inadequately filters user-supplied markup and emits content that can inject JavaScript into forum pages. An attacker must submit manipulated BBCode and another user must view the resulting content; scripts can expose private information or redirect that user.

CVSS severity6.1
Medium
EPSS probability0.82%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in XMB allows remote attackers to run browser scripts through crafted BBCode input viewed by other users. The BBCode processor inadequately filters user-supplied markup and emits content that can inject JavaScript into forum pages. An attacker must submit manipulated BBCode and another user must view the resulting content; scripts can expose private information or redirect that user.

The record

CVE
CVE-2021-29399
Published
Apr 19, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 19, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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