CVE-2023-25135
Published: April 11, 2026
Official Description
vBulletin before 5.6.9 PL1 allows an unauthenticated remote attacker to execute arbitrary code via a crafted HTTP request that triggers deserialization. This occurs because verify_serialized checks that a value is serialized by calling unserialize and then checking for errors. The fixed versions are 5.6.7 PL1, 5.6.8 PL1, and 5.6.9 PL1.
Risk Analysis
This vulnerability in vBulletin allows an unauthenticated remote attacker to execute arbitrary code through a crafted HTTP request that triggers deserialization. Its confirmed exploitation in the wild (is_in_kev: true) indicates a high and immediate risk, as it can lead to full system compromise without prior authentication.
This vulnerability has been actively exploited in the wild. It is remotely exploitable by an unauthenticated attacker via a crafted HTTP request.
vBulletin administrators should update their installations to versions 5.6.7 PL1, 5.6.8 PL1, or 5.6.9 PL1 or later to mitigate this deserialization vulnerability. Regularly monitor for suspicious network activity and ensure web application firewalls are configured to detect and block malicious requests.
Technical Analysis
CVE-2023-25135 requires local access, meaning attackers must already have a foothold on the target system.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
CISA has added CVE-2023-25135 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.
Exploit & PoC Resources
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2023-25135 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
- !CISA KEV: Federal agencies must patch per BOD 22-01 timeline
- !Active exploitation confirmed — treat as P1