CVE-2021-47934

Description

MyBB Timeline Plugin 1.0 contains cross-site scripting vulnerabilities that allow attackers to inject malicious scripts through thread titles, post content, and user profile fields like Location and Bio. Attackers can also exploit a cross-site request forgery vulnerability in the timeline.php profile action to change a user's cover picture by crafting malicious forms that execute when victims visit affected profiles.

Overview

State

—

Assigner (CNA)

—

CVSS severity

medium

CVSS score

5.3 / 10

CVSS vector

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Effective score

5.3 / 10 MEDIUM source: CNA overview

CWE(s)

—

Reserved

—

Published

—

Last updated

—

Source

https://www.tenable.com/cve/CVE-2021-47934

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published

2026-05-16 16:16:21 UTC

NVD last modified

2026-05-18 17:32:04 UTC

NVD CVSS v3.1

5.3 / 10 MEDIUM source: disclosure@vulncheck.com

NVD CVSS vector

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

Exploitability subscore

3.9 / 10

Impact subscore

1.4 / 10

EPSS score

0.0004 (probability of exploitation in next 30 days)

EPSS percentile

11.46% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

NVD-assigned CWE(s): CWE-79 (differs from the CNA list above)

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID

EUVD-2021-34840

Assigner

VulnCheck

Published

May 16, 2026, 3:26:03 PM

Updated

May 18, 2026, 1:43:44 PM

EUVD base score (CVSS 4.0)

6.9 / 10
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:L

EUVD-reported EPSS

0.0400

Vendors

MyBB

Products

MyBB Timeline Plugin (1.0)

Aliases

GHSA-9cv3-xr79-r4jw

ENISA description: MyBB Timeline Plugin 1.0 contains cross-site scripting vulnerabilities that allow attackers to inject malicious scripts through thread titles, post content, and user profile fields like Location and Bio. Attackers can also exploit a cross-site request forgery vulnerability in the timeline.php profile action to change a user's cover picture by crafting malicious forms that execute when victims visit affected profiles.

Vendor references (0)

References embedded in the original CVE record by the assigning CNA.

None in the CVE record.

Web references (6)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

• https://community.mybb.com/mods.php?action=view&pid=1428 tenable:community.mybb.com
• https://nvd.nist.gov/vuln/detail/CVE-2021-47934 tenable:nvd.nist.gov
• https://www.cve.org/CVERecord?id=CVE-2021-47934 tenable:www.cve.org
• https://www.exploit-db.com/exploits/49467 tenable:www.exploit-db.com
• https://www.first.org/epss/ tenable:www.first.org
• https://www.vulncheck.com/advisories/mybb-timeline-plugin-cross-site-scripting-and-csrf tenable:www.vulncheck.com

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