CVE-2026-5190 - AWS C Event Stream Streaming Decoder Stack Buffer Overflow

highCVE-2026-5190

Bulletin ID: 2026-011-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 2026/03/31 10:15 AM PDT Description: AWS Common Runtime library is used by several AWS SDKs to communicate with event-stream services (Ex. Kinesis, Transcribe). We identified CVE-2026-5190. AWS Common Runtime event-stream decoder component before 0.6.0 might allow a third party operating a server to cause memory corruption leading to arbitrary code execution on a client application that processes crafted event-stream messages. Impacted versions: - aws-c-event-stream < 0.6.0and the following higher level libraries that expose event-stream functionality - aws-iot-device-sdk-cpp-v2 < 1.42.1 - aws-iot-device-sdk-java-v2 < 1.30.1 - aws-iot-device-sdk-python-v2 < 1.28.2 - aws-iot-device-sdk-js-v2 < 1.25.1 - aws-sdk-swift < 1.6.70 - aws-sdk-cpp < 1.11.764 Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.

CSIRTS triage

vendor: AWS product: AWS Common Runtime Remote code executionOtheraffected: < 0.6.0

What: A stack buffer overflow in the event-stream decoder may allow a third party to cause memory corruption leading to arbitrary code execution.
Who is affected: Client applications using AWS Common Runtime versions before 0.6.0.
Urgency: Remediation is high priority due to the potential for arbitrary code execution.
Action: Upgrade to AWS Common Runtime version 0.6.0 or later.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: AWS Security Bulletins (INTL · vendor-psirt · site)
Severity: high
Published: 2026-06-05
Exploitation: Not in CISA KEV at last sync

Original advisory: https://aws.amazon.com/security/security-bulletins/rss/2026-011-aws/

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-51900.38% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 30% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-5190	coverage & exploitation status	NVD · CVE.org

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