IRONSMITHINTEL
CRITICALCVSS9.8
|
Actively Exploited
|CISA KEV|CVE-2020-17496|Auth: none — unauthenticated|Reboot: required|Manual only

vBulletin PHP Module Remote Code Execution Vulnerability

The PHP module within vBulletin contains an unspecified vulnerability that allows for remote code execution via crafted subWidgets data in an ajax/render/widget_tabbedcontainer_tab_panel request. This CVE ID resolves an incomplete patch for CVE-2019-16759.

Published Aug 12, 2020 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, without authentication, can achieve full data confidentiality loss, arbitrary modification of data, complete denial of service or system unavailability. Federal agencies are required to remediate by 2022-05-03 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Software Vulnerability (CWE-74) (CWE-74) vulnerability in vBulletin vBulletin. vBulletin 5.5.4 through 5.6.2 allows remote command execution via crafted subWidgets data in an ajax/render/widget_tabbedcontainer_tab_panel request. NOTE: this issue exists because of an incomplete fix for CVE-2019-16759. Exploitation requires remote network access, low attack complexity, no authentication required, and no user interaction required.

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Phishing link

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Malicious file

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Server compromised

Am I affected?Quick check

Probably yes if any of these apply:

IT Security
Running vbulletin: 5.5.4 ≤ v ≤ 5.6.2
Real-world incidentsWhat we've seen

Active exploitation documented in the wild. Threat-research write-up: https://blog.exploitee.rs/2020/exploiting-vbulletin-a-tale-of-patch-fail/

How to patch

Manual remediation steps

Apply the Vendor Patch

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog — apply the vendor's security update as soon as possible.

CISA required action: Apply updates per vendor instructions.

References

    1
    Vendor advisory: https://forum.vbulletin.com/forum/vbulletin-announcements/vbulletin-announcements_aa/4445227-vbulletin-5-6-0-5-6-1-5-6-2-security-patch
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2020-17496
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-17496
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