SEPTEMBER 14, 2026
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Case File

CVE-2026-73321

MEDIUM · CVSS 6.5 EPSS 0.40% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-09-08 · Last synced 2026-09-14

CyberRota Analysis

AI-Generated

XenForo versions prior to 2.3.13 are vulnerable to an uncontrolled recursion issue in the BBCode parser, which can be exploited by authenticated attackers to create a denial of service condition. By submitting a post with deeply nested BBCode tags, attackers can exceed PHP's stack limit, leading to repeated crashes of PHP-FPM workers and affecting all users accessing the impacted thread. Organizations using XenForo should prioritize this vulnerability to mitigate potential service disruptions.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-73321
Severity
MEDIUM
CVSS
6.5
EPSS
0.40%

Original NVD Description

XenForo before 2.3.13 contains an uncontrolled recursion vulnerability in the BBCode parser that allows authenticated attackers to cause persistent denial of service by submitting a post with deeply nested BBCode tags. Attackers can craft a single malicious post with sufficient nesting depth to exceed PHP's stack limit, causing fatal errors that repeatedly terminate PHP-FPM workers for all visitors rendering the affected thread.

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