CVE-2009-4247 in RealPlayer
Summary
by MITRE
Stack-based buffer overflow in protocol/rtsp/rtspclnt.cpp in RealNetworks RealPlayer 10; RealPlayer 10.5 6.0.12.1040 through 6.0.12.1741; RealPlayer 11 11.0.x; RealPlayer SP 1.0.0 and 1.0.1; RealPlayer Enterprise; Mac RealPlayer 10, 10.1, 11.0, and 11.0.1; Linux RealPlayer 10, 11.0.0, and 11.0.1; and Helix Player 10.x, 11.0.0, and 11.0.1 allows remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via an ASM RuleBook with a large number of rules, related to an "array overflow."
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Analysis
by VulDB Data Team • 04/29/2026
This vulnerability represents a critical stack-based buffer overflow in RealNetworks RealPlayer software across multiple versions and platforms. The flaw exists within the protocol/rtsp/rtspclnt.cpp file where the application fails to properly validate input data when processing ASM RuleBook structures containing an excessive number of rules. This allows remote attackers to manipulate the application's memory handling through specially crafted RTSP (Real Time Streaming Protocol) content that triggers an array overflow condition. The vulnerability affects a wide range of RealPlayer implementations including desktop, enterprise, and mobile versions across Windows, Mac, and Linux operating systems, making it particularly dangerous due to its broad impact surface.
The technical implementation of this vulnerability leverages a classic stack-based buffer overflow pattern where insufficient bounds checking occurs when processing the array of rules within the ASM RuleBook structure. When the application receives RTSP content with an excessive number of rules, it attempts to store this data in a fixed-size stack buffer without proper validation of the input length. This creates a condition where the buffer can be overwritten beyond its allocated memory boundaries, potentially corrupting adjacent stack memory and leading to application instability. The vulnerability operates at the protocol level through RTSP communications, making it accessible via network-based attacks without requiring local system access.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enabling remote code execution. While the primary effect manifests as application crashes and system instability, the buffer overflow condition creates opportunities for attackers to manipulate program execution flow through controlled memory corruption. This could allow malicious actors to inject and execute arbitrary code on vulnerable systems, particularly when the overflow affects critical function pointers or return addresses within the stack frame. The vulnerability's presence in enterprise and professional versions of RealPlayer makes it especially concerning for organizations that rely on these media players for business operations.
Mitigation strategies for this vulnerability require immediate patching of affected RealPlayer versions, with administrators prioritizing updates from RealNetworks to address the specific buffer overflow condition in the RTSP client implementation. System administrators should also implement network segmentation and firewall rules to limit RTSP traffic to trusted sources, reducing attack surface exposure. The vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which is categorized under the broader class of buffer overflow vulnerabilities that have been consistently identified as critical threats in cybersecurity assessments. From an ATT&CK framework perspective, this vulnerability maps to the T1203 Exploitation for Client Execution technique, where adversaries leverage application vulnerabilities to execute malicious code. Organizations should also consider implementing network monitoring solutions to detect unusual RTSP traffic patterns that might indicate exploitation attempts, while maintaining regular vulnerability assessments to identify similar issues in other media player implementations and streaming protocols.