CVE-2021-47934

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

• ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.23% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 13.9% of scored records. A rank, not a probability.

NVD base score

6.9 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

NVD analysis status

Deferred. NVD last modified this record on 2026-06-17.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2026-05-16 15:26Z5 MO AGO

Last updated

2026-05-18 13:43Z5 MO AGO

Reserved

2026-02-01

Assigning CNA

VulnCheck

Record state

PUBLISHED

Severity

Medium (CVSS 6.9)

CNA CVSS vector

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

Weaknesses

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

Data version

5.2

Document digest

4dc19f8732ba51f711c57fbf790c2ffd3d91aa6d0db978e3a0ed636afdabdda1

• www.exploit-db.comExploitDB-49467https://www.exploit-db.com/exploits/49467exploit
• community.mybb.comProduct Referencehttps://community.mybb.com/mods.php?action=view&pid=1428product
• www.vulncheck.comVulnCheck Advisory: MyBB Timeline Plugin 1.0 Cross-Site Scripting and CSRFhttps://www.vulncheck.com/advisories/mybb-timeline-plugin-cross-site-scripting-and-csrfthird-party-advisory