Security Advisory 2020-026

Release Date:

Critical Oracle WebLogic Server Vulnerability Exploited



  • 12/05/2020 --- v1.0 -- Initial publication


In April, within the monthly Critical Patch Update Advisory addressing hundreds of vulnerabilities [1], Oracle released an update about a critical vulnerability affecting WebLogic Server. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Oracle WebLogic. Authentication is not required to exploit this vulnerability. This bug, assigned with CVE-2020-2883, is now being reported by Oracle as being actively exploited in the wild [5].

Technical Details

The vulnerability was initially assigned with CVE-2020-2555 and patched by Oracle in January 2020 [2]. On 15th of January 2020, CERT-EU has issued Security Advisory 2020-004 that addressed, among others, CVE-2020-2555 as well [3].

However, according to Zero-Day Initiative, the patch made available in January by Oracle can by bypassed [4]. The specific flaw exists within the Oracle Coherence library. The issue results from the lack of proper validation of user-supplied data, which can result in deserialization of untrusted data. An attacker can leverage this vulnerability to execute code in the context of the service account. This by-pass has been patched in the April by Oracle as CVE-2020-2883. This vulnerability is now reported to be under active exploitation [5].

Affected Products

The vulnerability exists in Oracle WebLogic Server, versions,,, [1].


It is recommended to apply the necessary patches from the April Oracle Critical Patch Update [1] as soon as possible.







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