CVE-2026-55331 Overview
CVE-2026-55331 is an out-of-bounds write vulnerability in the IP Multimedia Subsystem (IMS) component. The flaw stems from an incorrect bounds check that allows attackers to write outside allocated memory buffers. Successful exploitation leads to remote code execution without requiring additional execution privileges. The vulnerability requires no user interaction, expanding the exploitation surface across affected devices. The issue is tracked under CWE-120: Buffer Copy without Checking Size of Input and was published in the Android Security Bulletin September 2026.
Critical Impact
Remote attackers can achieve code execution in the IMS component without user interaction, potentially compromising telephony and multimedia services on affected devices.
Affected Products
- Android devices implementing the vulnerable IP Multimedia Subsystem component
- Google Pixel devices covered by the September 2026 security bulletin
- Downstream Android distributions incorporating the affected IMS code
Discovery Timeline
- 2026-09-15 - CVE-2026-55331 published to the National Vulnerability Database
- 2026-09-16 - Last updated in NVD database
Technical Details for CVE-2026-55331
Vulnerability Analysis
The vulnerability resides in the IP Multimedia Subsystem (IMS), a core Android component responsible for handling voice, video, and messaging services over IP networks. An incorrect bounds check in the IMS code path allows an attacker-controlled input to trigger a write beyond the allocated buffer boundary. Out-of-bounds writes in native components typically corrupt adjacent heap metadata, function pointers, or return addresses. Attackers can leverage this corruption to hijack control flow and execute arbitrary code within the IMS process context.
Root Cause
The root cause is classified under CWE-120: Buffer Copy without Checking Size of Input. The IMS component fails to properly validate the size of incoming data against the destination buffer capacity before performing a memory write operation. This missing or incorrect length validation allows an attacker to supply input that exceeds the expected boundary, resulting in memory corruption.
Attack Vector
The attack vector is network-based and requires low privileges but no user interaction. An attacker within reach of the target IMS service can send crafted signaling or media traffic to trigger the out-of-bounds write. Because IMS handles telephony session establishment, malicious traffic can reach the vulnerable code path through standard mobile network protocols. Successful exploitation grants code execution within the IMS component and can serve as a pivot point for privilege escalation or persistence.
No verified proof-of-concept code is publicly available. Refer to the Android Security Bulletin September 2026 for vendor-provided technical details.
Stop Remote Code Execution Before It Runs
Singularity™ Endpoint detects and blocks exploit attempts at machine speed, including zero-days and novel attack techniques.
Stop Exploit AttemptsDetection Methods for CVE-2026-55331
Indicators of Compromise
- Unexpected crashes, restarts, or memory corruption signatures in the IMS service or related telephony processes
- Anomalous IMS signaling traffic containing malformed length fields or oversized payloads
- Native code execution or shell activity spawned from telephony-related process contexts
Detection Strategies
- Monitor Android system logs for repeated IMS process crashes, tombstones, or SIGSEGV events that may indicate exploitation attempts
- Inspect network telemetry for anomalous SIP, RTP, or IMS signaling packets targeting mobile endpoints
- Correlate telephony subsystem anomalies with subsequent privilege escalation or lateral movement events
Monitoring Recommendations
- Enable mobile threat defense telemetry to capture native crash reports from IMS and related components
- Track patch level compliance across the Android fleet against the September 2026 security bulletin
- Alert on newly spawned processes or unexpected network connections originating from telephony service contexts
How to Mitigate CVE-2026-55331
Immediate Actions Required
- Apply the September 2026 Android security patch level or later to all affected devices as soon as available from the device vendor
- Inventory managed mobile devices and identify those running Android security patch levels prior to 2026-09-01
- Prioritize patch deployment on devices exposed to untrusted mobile networks or roaming environments
Patch Information
Google addressed CVE-2026-55331 in the September 2026 Android Security Bulletin. Device manufacturers must integrate the fix into their vendor-specific builds. Refer to the Android Security Bulletin September 2026 for the definitive list of patched components and required security patch level.
Workarounds
- No official vendor workaround exists; patching is the only supported remediation
- Restrict device connectivity to trusted mobile networks where feasible until patches are deployed
- Enforce mobile device management policies that block or quarantine devices running unpatched Android versions
Refer to vendor documentation for configuration steps specific to your mobile device management platform.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
