Two essential vulnerabilities affecting the open-source discussion board software program vBulletin have been found, with one confirmed to be actively exploited within the wild.
The failings, tracked below CVE-2025-48827 and CVE-2025-48828, and rated essential (CVSS v3 rating: 10.0 and 9.0 respectively), are an API methodology invocation and a distant code execution (RCE) by way of template engine abuse flaws.
They impression vBulletin variations 5.0.0 by means of 5.7.5 and 6.0.0 by means of 6.0.3 when the platform runs on PHP 8.1 or later.
The vulnerabilities have been possible patched quietly final 12 months with the discharge of Patch Degree 1 for all variations of the 6.* launch department, and model 5.7.5 Patch Degree 3, however many websites remained uncovered resulting from not upgrading.
Public PoC and energetic exploitation
The 2 points have been found on Could 23, 2025, by safety researcher Egidio Romano (EgiX), who defined exploit it by way of an in depth technical publish on his weblog.
The researcher confirmed that the flaw lies in vBulletin’s misuse of PHP’s Reflection API, which, resulting from behavioral adjustments launched in PHP 8.1, permits protected strategies to be invoked with out express accessibility changes.
The vulnerability chain lies within the capacity to invoke protected strategies by way of crafted URLs and the misuse of template conditionals inside vBulletin’s template engine.
By injecting crafted template code utilizing the weak ‘replaceAdTemplate’ methodology, attackers bypass “unsafe perform” filters utilizing tips like PHP variable perform calls.
This ends in absolutely distant, unauthenticated code execution on the underlying server — successfully granting attackers shell entry as the online server person (www-data on Linux, for instance).
On Could 26, safety researcher Ryan Dewhurst reported seeing exploitation makes an attempt on honeypot logs displaying requests to the weak ‘ajax/api/advert/replaceAdTemplate’ endpoint.
Supply:Â weblog.kevintel.com
Dewhurst traced one of many attackers to Poland, seeing makes an attempt to deploy PHP backdoors to execute system instructions.
The researcher famous that the assaults look like leveraging the exploit revealed earlier by Romano, although there have been Nuclei templates accessible for the flaw since Could 24, 2025.
It is very important make clear that Dewhurst solely noticed exploitation makes an attempt for CVE-2025-48827, however no proof exists but that attackers have efficiently chained it to the complete RCE, though that is extremely possible.
vBulletin troubles
vBulletin is among the most generally used industrial PHP/MySQL-based discussion board platforms, powering hundreds of on-line communities globally.
Its modular design, together with cell APIs and AJAX interfaces, makes it a fancy and versatile platform. Nevertheless, it additionally exposes a broad assault floor.
Previously, hackers have leveraged extreme flaws within the platform to breach common boards and steal the delicate information of massive numbers of customers.
Discussion board directors are advisable to use the safety updates for his or her vBulletin set up or transfer to the newest launch, model 6.1.1, which isn’t affected by the mentioned flaws.
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