Two important 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 underneath CVE-2025-48827 and CVE-2025-48828, and rated important (CVSS v3 rating: 10.0 and 9.0 respectively), are an API methodology invocation and a distant code execution (RCE) through template engine abuse flaws.
They influence vBulletin variations 5.0.0 by way of 5.7.5 and 6.0.0 by way of 6.0.3 when the platform runs on PHP 8.1 or later.
The vulnerabilities had 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 as a consequence of not upgrading.
Public PoC and energetic exploitation
The 2 points had been found on Might 23, 2025, by safety researcher Egidio Romano (EgiX), who defined how one can exploit it through an in depth technical submit on his weblog.
The researcher confirmed that the flaw lies in vBulletin’s misuse of PHP’s Reflection API, which, as a consequence of behavioral adjustments launched in PHP 8.1, permits protected strategies to be invoked with out specific accessibility changes.
The vulnerability chain lies within the skill to invoke protected strategies through 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 leads to totally distant, unauthenticated code execution on the underlying server — successfully granting attackers shell entry as the online server consumer (www-data on Linux, for instance).
On Might 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: 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 seem like leveraging the exploit revealed earlier by Romano, although there have been Nuclei templates out there for the flaw since Might 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 without doubt one of the most generally used industrial PHP/MySQL-based discussion board platforms, powering 1000’s of on-line communities globally.
Its modular design, together with cellular APIs and AJAX interfaces, makes it a fancy and versatile platform. Nonetheless, it additionally exposes a broad assault floor.
Up to now, hackers have leveraged extreme flaws within the platform to breach standard boards and steal the delicate knowledge of massive numbers of customers.
Discussion board directors are really useful to use the safety updates for his or her vBulletin set up or transfer to the most recent launch, model 6.1.1, which isn’t affected by the mentioned flaws.
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