AWS Advises on CVE-2026-5190: Stack Buffer Overflow in C Event Stream Decoder
Amazon Web Services has issued a security bulletin regarding a stack buffer overflow vulnerability in its C Event Stream Streaming Decoder.
Key points
- AWS identified CVE-2026-5190 as a stack buffer overflow in the C Event Stream Streaming Decoder.
- The vulnerability is classified under the AWS Security Bulletins program.
- No specific CVSS score or patch availability is detailed in the initial advisory title.
Amazon Web Services (AWS) has released a security bulletin addressing CVE-2026-5190, a stack buffer overflow vulnerability located within the AWS C Event Stream Streaming Decoder. The advisory highlights a flaw that could potentially allow an attacker to exploit the decoder component, though specific technical details regarding the exploit mechanism are limited in the initial release.
The vulnerability, tracked as CVE-2026-5190, affects the C-based implementation of the Event Stream Streaming Decoder. This component is part of AWS’s infrastructure for handling event data streams, which are critical for various serverless and streaming services. A stack buffer overflow occurs when a program writes more data to a buffer than it can hold, potentially overwriting adjacent memory. In the context of a streaming decoder, this could lead to unexpected behavior, crashes, or potentially code execution if an attacker can control the input data processed by the decoder.
Context and Background
AWS Security Bulletins are regular updates that provide information about security vulnerabilities affecting AWS services and infrastructure. These bulletins are designed to help customers understand potential risks and take appropriate actions to secure their environments. The release of this specific bulletin indicates that AWS has identified a significant issue within its internal or customer-facing software components.
The C Event Stream Streaming Decoder is a specialized tool used to parse and process event data in a continuous stream. Event streams are fundamental to many modern cloud architectures, enabling real-time data processing and integration between different services. Vulnerabilities in such core components can have widespread implications, as they may affect multiple services that rely on the decoder for data ingestion and processing.
Who Is Affected
While the advisory does not explicitly list all affected services, any AWS customer or service that utilizes the C Event Stream Streaming Decoder may be impacted. This likely includes users of AWS Lambda, Kinesis Data Streams, and other services that process event data in real-time. Organizations that have custom integrations or applications relying on this specific decoder component should review their configurations and data handling practices.
The potential impact of CVE-2026-5190 depends on how the decoder is deployed and whether it is exposed to untrusted input. If the decoder processes data from external sources without adequate validation, the risk of exploitation increases. Customers should assess their use of event streaming services and determine if they are using the affected C-based decoder.
What should you do?
AWS has not provided a specific mitigation or patch in the initial bulletin title. Customers should monitor AWS Security Bulletins for further updates and guidance. It is recommended to review the security configuration of any services that process event streams, ensuring that input validation and data integrity checks are in place. Organizations should also verify that their monitoring and logging capabilities are sufficient to detect unusual activity related to event stream processing.
What to do and how to stay safe: AWS
- Review AWS Security Bulletins regularly for updates on CVE-2026-5190 and other vulnerabilities.
- Audit your use of AWS event streaming services to identify if the C Event Stream Streaming Decoder is in use.
- Implement strict input validation for any data processed by event stream decoders to prevent malformed inputs.
- Monitor logs and alerts for unusual activity or errors in event stream processing components.
Step-by-step guide: Risk Based Vulnerability Management: Prioritize Fixes by Actual Threat
General security guidance from the Threat Times newsroom. It is not confirmed advice from the organisations named in this story.
Frequently asked questions
What is CVE-2026-5190?
CVE-2026-5190 is a stack buffer overflow vulnerability in the AWS C Event Stream Streaming Decoder.
Is there a patch available for CVE-2026-5190?
The initial advisory does not confirm the availability of a patch; customers should wait for further updates from AWS.
Which AWS services might be affected by this vulnerability?
Services that utilize the C Event Stream Streaming Decoder, such as AWS Lambda and Kinesis Data Streams, may be affected.
