CVE-2026-56974 Overview
CVE-2026-56974 is an out-of-bounds write vulnerability in the Start function of AudioRtpPayloadEncoderNode.cpp, an Android component that processes Real-time Transport Protocol (RTP) audio payloads. The flaw stems from improper input validation [CWE-20] and can lead to remote code execution without requiring additional execution privileges. Exploitation requires user interaction. Google disclosed the issue in the Android Security Bulletin dated September 1, 2026.
Critical Impact
Attackers can achieve remote code execution on affected Android devices by delivering a crafted RTP audio payload that triggers an out-of-bounds write during encoder initialization.
Affected Products
- Android platform components processing RTP audio payloads (AudioRtpPayloadEncoderNode)
- Pixel devices covered by the September 2026 Android Security Bulletin
- Refer to the Android Security Bulletin September 2026 for the definitive list of affected builds
Discovery Timeline
- 2026-09-15 - CVE-2026-56974 published to the National Vulnerability Database
- 2026-09-16 - Last updated in NVD database
Technical Details for CVE-2026-56974
Vulnerability Analysis
The vulnerability resides in the Start method of AudioRtpPayloadEncoderNode.cpp, a component responsible for initializing an RTP audio encoding pipeline on Android. The code fails to validate input parameters used during buffer setup or payload configuration. As a result, an attacker-influenced value can drive a write past the bounds of an allocated buffer. Out-of-bounds writes in native C++ media components frequently enable memory corruption primitives sufficient for arbitrary code execution.
The issue is categorized as Improper Input Validation [CWE-20]. The Exploit Prediction Scoring System (EPSS) currently rates the near-term exploitation probability as low, and no public proof-of-concept or in-the-wild exploitation has been reported.
Root Cause
The root cause is missing or insufficient validation of input parameters supplied to AudioRtpPayloadEncoderNode::Start. When the encoder node initializes, downstream buffer arithmetic operates on untrusted or unchecked values, allowing a write outside the intended memory region. Media pipeline components run in privileged native processes, which increases the impact of memory corruption within them.
Attack Vector
The attack vector is network-based but requires user interaction, consistent with typical Android RTP-related flaws such as incoming Voice-over-IP (VoIP) calls or media stream negotiation. An attacker delivers a crafted RTP audio session that the target user accepts or acts upon, triggering the vulnerable code path in the encoder node. Because the flaw permits remote code execution without additional privileges, successful exploitation grants the attacker execution within the affected media process context.
No verified public exploitation code is available. See the Android Security Bulletin September 2026 for vendor-provided technical detail and patch references.
Detection Methods for CVE-2026-56974
Indicators of Compromise
- Unexpected crashes or tombstone entries referencing AudioRtpPayloadEncoderNode or the media codec process on affected Android builds
- Anomalous inbound RTP/SIP traffic to devices from untrusted peers, particularly sessions terminated abruptly after audio negotiation
- Post-crash spawning of unexpected child processes by media-related services
Detection Strategies
- Monitor Android device logs (logcat, tombstones, dropbox) for repeated native crashes in RTP or audio encoder components
- Inspect network telemetry for malformed or unusually structured SIP/RTP signaling directed at mobile endpoints
- Correlate media process crashes with preceding inbound call or streaming session events to identify targeted exploitation attempts
Monitoring Recommendations
- Enroll mobile devices in a Mobile Device Management (MDM) or Mobile Threat Defense (MTD) platform capable of surfacing OS patch level and native crash telemetry
- Track Android security patch level compliance against the September 2026 bulletin across the fleet
- Alert on devices that remain below the required patch level after the maintenance window
How to Mitigate CVE-2026-56974
Immediate Actions Required
- Apply the September 2026 Android security patch level (or later) to all affected devices as soon as it is available from the device manufacturer
- Prioritize patching for users who receive RTP-based communications such as VoIP or video conferencing calls from external parties
- Educate users to reject or ignore unexpected calls and media invitations from unknown contacts until patched
Patch Information
Google addressed CVE-2026-56974 in the September 2026 Android Security Bulletin. Fix details and affected build identifiers are published in the Android Security Bulletin September 2026. Device manufacturers distribute the corresponding firmware updates according to their own release schedules; verify the device reports a security patch level of 2026-09-01 or later.
Workarounds
- No vendor-supplied workaround is documented; patching is the authoritative remediation
- Where patching is delayed, restrict VoIP and RTP-capable applications to trusted contacts and disable auto-answer features
- Enforce network-level controls that block unsolicited SIP/RTP sessions to managed mobile endpoints
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.