CVE-2026-112060 in librtmp
Summary
by MITRE • 10/18/2026
librtmp in RTMPDump through 2.6 contains an out-of-bounds read and heap out-of-bounds write vulnerability because AMF3_Decode ignores AMF3 property decode failures. Malicious RTMP servers or man-in-the-middle attackers can send oversized AMF3 string lengths, and with the token option DecodeTEA corrupts heap memory and leaks heap bytes.
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Analysis
by VulDB Data Team • 10/18/2026
The librtmp library, a core component of the RTMPDump suite up to version 2.6, contains critical memory safety vulnerabilities that compromise the integrity and confidentiality of data processed during Real-Time Messaging Protocol communications. These flaws stem from insufficient validation of input parameters within the AMF3 decoding logic, specifically affecting how property decode failures are handled. The vulnerability manifests in two distinct but related forms: an out-of-bounds read and a heap-based buffer overflow write. This lack of rigorous boundary checking allows malicious actors to exploit the parser's behavior when processing malformed or specially crafted AMF3 data structures sent by untrusted sources, such as rogue RTMP servers or attackers positioned for man-in-the-middle interception.
The technical root cause lies in the AMF3_Decode function, which is responsible for parsing Action Message Format version 3 payloads. When decoding properties, the library fails to properly validate string lengths and handle decode errors gracefully. Specifically, if an attacker provides oversized AMF3 string length values, the parser does not adequately check whether these dimensions fit within allocated memory buffers before proceeding with read or write operations. In scenarios where the DecodeTEA token option is enabled, this oversight leads directly to heap corruption. The application attempts to access or modify memory locations beyond the bounds of the allocated buffer, resulting in a heap out-of-bounds write that can overwrite adjacent data structures and potentially allow for arbitrary code execution if an attacker can control the overwritten content.
Simultaneously, the failure to handle decode failures correctly results in an out-of-bounds read vulnerability. When processing malformed AMF3 objects with invalid length fields, the parser may attempt to read memory locations outside the intended buffer boundaries. This behavior leads to a heap information leak, where sensitive data residing in adjacent memory regions is exposed to the attacker. Such leaks can reveal internal application states, cryptographic keys, or other confidential information that aids further exploitation of the system. The combination of these two flaws creates a severe security risk, as an adversary could potentially combine information leakage with code execution capabilities to achieve full compromise of the affected software environment.
From a classification perspective, this vulnerability aligns with CWE-125 (Out-of-bounds Read) and CWE-787 (Out-of-bounds Write), both of which represent fundamental memory safety errors common in C-based applications that do not perform strict input validation. The exploitation vector falls under ATT&CK technique T1059, specifically Command Line Interface or Scripting Interpreter abuse if the heap corruption leads to code execution, and potentially T1048 (Exfiltration Over Alternative Protocol) due to the information leakage aspect via RTMP streams. These classifications highlight the severity of bypassing standard input validation protocols in network-facing services that process complex binary data formats like AMF3.
The operational impact of these vulnerabilities is significant for any service relying on librtmp for streaming media ingestion or playback. An attacker with the ability to inject malicious AMF3 payloads into an RTMP stream can crash the application through segmentation faults caused by invalid memory access, leading to denial-of-service conditions. More critically, successful exploitation could allow remote code execution, granting the attacker control over the host system running the vulnerable library. This is particularly dangerous in environments where librtmp is used for automated media processing pipelines or client applications that connect to untrusted streaming servers without sufficient sandboxing or isolation mechanisms.
Mitigation strategies must focus on immediate patching and defensive coding practices. The primary remediation is to upgrade librtmp to a version beyond 2.6, where these parsing flaws have been addressed with proper bounds checking and error handling for AMF3 property decoding. For systems that cannot be immediately updated, implementing network-level filtering to inspect RTMP traffic for anomalous string lengths or malformed AMF structures can provide a layer of defense-in-depth. Additionally, enabling Address Sanitizer (ASan) during development and testing phases helps identify such memory errors early in the software lifecycle. Developers should also enforce strict input validation on all external data sources, ensuring that length fields are verified against allocated buffer sizes before any read or write operations are attempted, thereby preventing both out-of-bounds reads and writes from occurring.