CVE-2026-85150 in Red Hat
Summary
by MITRE • 09/03/2026
A NULL pointer dereference flaw was found in GStreamer's RTSP support library. The vulnerability occurs while parsing an Authorization or WWW-Authenticate header that uses Digest authentication. Specially crafted whitespace placement around a parameter's terminator can cause an internal length calculation to underflow, leading to a crash of the process parsing the header. On an RTSP server this can be triggered by a remote, unauthenticated attacker sending a single malformed request when the server has authentication enabled; the same flaw can also be triggered against an RTSP client by a malicious or compromised RTSP server. Successful exploitation results in a denial of service (application crash) and has no confirmed impact on confidentiality or integrity.
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Analysis
by VulDB Data Team • 09/03/2026
The vulnerability identified as a NULL pointer dereference within GStreamer's Real Time Streaming Protocol support library represents a significant stability risk for applications relying on this framework for media streaming operations. The flaw is specifically located in the parsing logic responsible for handling HTTP-style authentication headers, namely Authorization and WWW-Authenticate fields that utilize Digest authentication mechanisms. This component of the software is critical for establishing secure communication channels between RTSP clients and servers by verifying credentials before allowing access to protected streams or resources. When a request containing these headers reaches the parser, it undergoes several stages of validation and length calculation to determine parameter boundaries and content integrity.
The technical root cause of this vulnerability lies in an integer underflow condition triggered by specific whitespace manipulation within the header parameters. During the parsing process, the library calculates the length of certain authentication parameters based on their terminators and surrounding characters. An attacker can craft a malformed request where whitespace is strategically placed around parameter terminators to disrupt these internal calculations. This deliberate misalignment causes the arithmetic operation used to determine string lengths or buffer offsets to underflow, resulting in an extremely large positive value being interpreted as a negative index or causing subsequent pointer arithmetic to wrap around memory addresses incorrectly. Consequently, when the application attempts to access data at this invalid location, it triggers a NULL pointer dereference exception because the calculated address resolves to zero or another unmapped region that results in a null reference during execution.
From an operational perspective, this vulnerability leads directly to a denial of service condition characterized by the immediate crash of the process responsible for parsing the RTSP traffic. For RTSP servers with authentication enabled, a remote unauthenticated attacker can exploit this flaw simply by sending a single malformed request containing the specially crafted header fields. The server application will terminate unexpectedly upon processing this input, effectively halting all streaming services hosted on that instance and requiring manual intervention or automatic restart mechanisms to restore availability. Similarly, RTSP clients are also vulnerable if they connect to malicious or compromised servers that serve these malformed headers in their responses. In such scenarios, the client application crashes when attempting to parse the server's authentication challenge, disrupting media playback and potentially causing data loss for any ongoing streaming sessions without warning.
The impact of this vulnerability is strictly limited to availability due to the application crash, with no confirmed implications for confidentiality or integrity at this time. The NULL pointer dereference does not inherently allow for arbitrary code execution or memory corruption that could be leveraged to read sensitive information from process memory or modify system state beyond the immediate termination of the vulnerable thread or process. However, in high-availability environments where GStreamer is used for critical infrastructure such as surveillance systems, live broadcasting platforms, or industrial control interfaces, repeated exploitation can lead to significant operational downtime and service degradation. The lack of confirmed lateral movement capabilities reduces the severity from a potential remote code execution risk but maintains it as a serious availability threat that requires prompt remediation.
Mitigation strategies should focus on both immediate patching and architectural defenses. Users running affected versions of GStreamer must update to patched releases where the parsing logic has been corrected to handle edge cases in whitespace and parameter termination robustly, ensuring that length calculations do not underflow even with malformed input. In environments where updating is not immediately feasible, deploying network-level protections such as intrusion prevention systems or web application firewalls can help filter out suspicious RTSP traffic patterns before they reach the vulnerable GStreamer components. These security devices should be configured to detect and block requests containing anomalous whitespace structures in authentication headers that deviate from standard RFC compliance for Digest authentication schemes. Additionally, implementing robust error handling and process monitoring within applications using GStreamer can facilitate faster recovery times by automatically restarting crashed services when such exceptions occur, thereby minimizing the duration of service interruption caused by this denial-of-service vector.
This vulnerability aligns with Common Weakness Enumeration category CWE-476 which describes NULL Pointer Dereference flaws that lead to application crashes or unexpected behavior. It also maps to MITRE ATT&CK technique T1499 Endpoint Denial of Service, specifically under the sub-category of Resource Exhaustion via Crash, as it involves exhausting system resources by causing a critical process failure through malformed input rather than consuming CPU or memory indefinitely. Understanding these classifications helps security teams prioritize remediation efforts and communicate the risk profile accurately to stakeholders involved in maintaining secure streaming infrastructure.