CVE-2021-21783: Genivia Gsoap RCE Vulnerability

CVE-2021-21783 Overview

CVE-2021-21783 is a remote code execution vulnerability in the WS-Addressing plugin functionality of Genivia gSOAP version 2.8.107. A specially crafted Simple Object Access Protocol (SOAP) request triggers the flaw, allowing attackers to execute arbitrary code on affected systems. The vulnerability is reachable over the network through a standard HTTP request, requires no authentication, and needs no user interaction.

The weakness is classified under CWE-680 (Integer Overflow to Buffer Overflow) and CWE-190 (Integer Overflow or Wraparound). gSOAP is widely embedded in enterprise products, including multiple Oracle Communications platforms.

Critical Impact
Unauthenticated attackers can achieve remote code execution by sending a single crafted SOAP request to any service built on the affected gSOAP library.

Affected Products

Genivia gSOAP 2.8.107
Oracle Communications Diameter Signaling Router, Eagle Application Processor, and Eagle LNP Application Processor (46.7, 46.8, 46.9)
Oracle Communications LSMS (13.1 through 13.4) and Oracle Tekelec Virtual Operating Environment

Discovery Timeline

2021-03-25 - CVE-2021-21783 published to the National Vulnerability Database (NVD)
2021-10 - Oracle addresses downstream impact in the Oracle Security Alert October 2021
2022-01 - Oracle issues additional fixes in the Oracle Security Alert January 2022
2024-11-21 - Last updated in the NVD database

Technical Details for CVE-2021-21783

Vulnerability Analysis

The flaw resides in the WS-Addressing plugin shipped with gSOAP, a C/C++ toolkit used to build SOAP and XML-based web services. When the plugin parses inbound SOAP envelopes containing WS-Addressing headers, an integer overflow occurs during size or length computation. The overflowed value is then used to govern a memory operation, producing an out-of-bounds write that corrupts adjacent memory regions.

Because gSOAP runs inside the service process, successful exploitation grants the attacker the privileges of that process. In many embedded telecommunications and enterprise deployments, gSOAP-based daemons operate with elevated privileges, increasing the value of a successful exploit. Refer to the Talos Intelligence Vulnerability Report for the disclosure write-up.

Root Cause

The root cause is an integer overflow ([CWE-190]) within the WS-Addressing message handling path. An attacker-controlled length value wraps past the maximum representable integer, producing a small computed buffer size that is later used in operations expecting a larger allocation. The mismatch triggers an integer-overflow-to-buffer-overflow condition ([CWE-680]), corrupting heap or stack memory.

Attack Vector

The attack vector is network-based and unauthenticated. An attacker delivers a malicious SOAP envelope to any HTTP endpoint that uses the vulnerable gSOAP runtime with the WS-Addressing plugin enabled. The crafted message contains WS-Addressing header values designed to trigger the integer overflow during parsing. No prior session, credential, or user interaction is required for exploitation.

No public proof-of-concept exploit code is currently available for CVE-2021-21783, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. The EPSS probability is 2.056% with a percentile of 84.069, indicating elevated relative exploitation likelihood compared to the broader CVE population.

Detection Methods for CVE-2021-21783

Indicators of Compromise

Unexpected crashes, segmentation faults, or restarts of services linking the gSOAP runtime, particularly under SOAP traffic load.
HTTP POST requests containing SOAP envelopes with abnormally large or malformed WS-Addressing header values (wsa:To, wsa:Action, wsa:MessageID, wsa:ReplyTo).
Child process creation or shell invocation originating from a SOAP service process.
Outbound network connections from web service daemons to unfamiliar hosts shortly after inbound SOAP traffic.

Detection Strategies

Inspect SOAP traffic at the application layer to flag malformed or oversized WS-Addressing elements.
Hunt for anomalous child processes spawned by gSOAP-linked binaries or Oracle Communications service processes.
Correlate crash telemetry with inbound HTTP requests targeting /soap, /ws, or other SOAP endpoints.

Monitoring Recommendations

Enable verbose logging on SOAP-handling services and forward logs to a centralized analytics platform.
Monitor for unusual memory allocation patterns, segfault counts, and crash-loop behavior on telephony and signaling infrastructure.
Track outbound connections initiated by service accounts that host gSOAP-based applications.

How to Mitigate CVE-2021-21783

Immediate Actions Required

Inventory all systems that embed gSOAP 2.8.107 or that ship Oracle Communications products listed in the affected products section.
Apply the relevant Oracle Critical Patch Updates from October 2021 and January 2022 to all affected Oracle Communications deployments.
Upgrade Genivia gSOAP to a version later than 2.8.107 that incorporates the upstream fix.
Restrict network exposure of SOAP endpoints to trusted management networks until patches are deployed.

Patch Information

Genivia released a fixed version of gSOAP following coordinated disclosure through Cisco Talos. Oracle published downstream remediations in the Oracle Security Alert October 2021 and Oracle Security Alert January 2022. Administrators of Oracle Communications Diameter Signaling Router, Eagle Application Processor, Eagle LNP Application Processor, LSMS, and Tekelec Virtual Operating Environment should apply the corresponding CPUs.

Workarounds

Place affected SOAP endpoints behind a web application firewall (WAF) configured to inspect and size-limit WS-Addressing header fields.
Disable the WS-Addressing plugin where it is not required by application functionality.
Enforce strict network segmentation so only authorized management hosts can reach SOAP services.
Apply request size limits and schema validation at upstream reverse proxies to drop malformed SOAP envelopes.

bash

# Example NGINX configuration to limit SOAP request size and restrict access
location /soap {
    client_max_body_size 64k;
    allow 10.0.0.0/8;
    deny all;
    proxy_pass http://backend_soap_service;
}