CVE intelligence and bounded remediation
CVE-2019-18873 — FUDForum 3.0.9 is vulnerable to Stored XSS via the User-Agent HTTP header
FUDForum 3.0.9 is vulnerable to Stored XSS via the User-Agent HTTP header. This may result in remote code execution. An attacker can use a user account to fully compromise the system via a GET request. When the admin visits user information under "User Manager" in the control panel, the payload will execute. This will allow for PHP files to be written to the web root, and for code to execute on the remote server. The problem is in admsession.php and admuser.php.
- Severity
- Critical
- CVSS
- 9 (3.1)
- Published
- 2019-11-12
- CISA KEV
- Not currently listed
- Ecosystem
- software/application
- Weaknesses
- CWE-78, CWE-79
Affected products
- fudforum / fudforum / 3.0.9
Matched remediation archetype
Command, code, expression, and template injection
This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.
Check exposure
- Trace untrusted values to process execution, interpreters, evaluators, template engines, dynamic imports, and administrative scripting features.
- Determine whether the affected path is reachable across each trust boundary and which service account or host privilege it inherits.
- Review configuration for optional execution features, unsafe compatibility modes, and shell invocation.
Remediate safely
- Replace string-built commands or evaluated code with fixed operations and structured argument APIs that do not invoke a shell.
- Use strict allowlists for operation identifiers and reject unexpected input before it reaches any interpreter.
- Update the affected component and add inert regression tests covering metacharacters, encoding variants, and alternate request paths.
Authoritative sources
Complete CVE record and remediation plan
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