Mandiant Uncovers WAF Bypass Campaign Exploiting Critical Oracle PeopleSoft CVE-2026-35273
Mandiant has identified an active campaign abusing CVE-2026-35273, a critical unauthenticated remote code execution flaw in Oracle PeopleSoft's Environment Management Hub (PSEMHUB). Attackers bypass web application firewalls by replacing the literal path /PSEMHUB/ with /%50SEMHUB/, exploiting the fact that many WAF rules inspect the URL before decoding while the PeopleSoft application server decodes it afterward. The exploitation chain relies on Java object deserialization via POST requests to /%50SEMHUB/hub, allowing deployment of two distinct JSP web shells. The group then establishes persistence with a trojanized installer that drops the SIDEEYE backdoor along with Neo-reGeorg and MeshAgent. Activity attributed to UNC6240, linked to ShinyHunters, began as a zero-day against educational institutions in June 2026 and has since expanded to higher education, technology, healthcare, agriculture, transportation, and government sectors.
BoletimSecSep 28, 2026Translated from Portuguese