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Fencer Vulns
critical 9.0

CVE-2019-18873 json

FUDForum 3.0.9 is vulnerable to Stored XSS via the User-Agent HTTP header.

published 2019-11-12 6 y ago modified 2026-06-17 4 mo ago also EUVD-2019-8568

cvss
9.0
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
8.2%
EPSS 8.2% chance of exploitation in 30 days, percentile 94%
public exploits
1
Exploit-DB

Summary

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.

Timeline

  1. Published
  2. First public exploit (EDB-47650)

Exploit prediction

8.15% chance of exploitation in the next 30 days, higher than 94% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • EDB-47650 FUDForum 3.0.9 - Remote Code Execution webapps, 2019-11-13
  • github.com https://github.com/fuzzlove/FUDforum-XSS-RCE referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
NVD 2.0 8.5 AV:N/AC:M/Au:S/C:C/I:C/A:C

Classification

Weakness
  • CWE-78 Improper Neutralization of Special Elements used in an OS Command
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.