CVE-2026-19643 in aws-sdk-cpp
Summary
by MITRE • 08/12/2026
An out-of-bounds read issue in the Base64 decoder in Amazon aws-sdk-cpp before 1.11.862, on some platforms, might allow a remote authenticated user to crash an application that processes crafted Base64-encoded input.
To remediate this issue, users should upgrade to version 1.11.862.
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Analysis
by VulDB Data Team • 08/12/2026
This vulnerability represents a critical out-of-bounds read condition within the Base64 decoding implementation of the AWS SDK for C++ library. The flaw manifests when applications process maliciously crafted Base64-encoded input data through the affected library components. Such vulnerabilities fall under the CWE-129 weakness category, specifically addressing issues related to improper validation of input boundaries during buffer operations. The vulnerability affects versions prior to 1.11.862 and demonstrates how seemingly benign encoding operations can become attack vectors when proper boundary checks are absent.
The technical execution of this vulnerability occurs through authenticated remote exploitation where an attacker can craft specific Base64 input sequences that cause the decoder to access memory locations beyond the allocated buffer boundaries. This type of out-of-bounds read represents a fundamental memory safety issue that can lead to application crashes, data corruption, or potentially more severe consequences depending on the execution environment. The vulnerability's impact is particularly concerning because it affects applications that process external input through the AWS SDK, creating multiple potential attack vectors across different AWS service integrations.
From an operational perspective, this vulnerability creates significant risk for applications that rely on the AWS SDK for C++ to handle Base64-encoded data from untrusted sources. The attack surface expands to include any application component that processes user-provided data through the affected library functions, potentially leading to denial of service conditions or system instability. The remote authenticated nature of the vulnerability means that attackers do not require direct system access but can exploit the weakness through legitimate authentication mechanisms, making it particularly dangerous in production environments where applications process external input.
The remediation approach requires immediate upgrading to version 1.11.862 or later, which incorporates proper boundary checking mechanisms within the Base64 decoding implementation. Organizations should prioritize this update across all systems that utilize the affected AWS SDK components, particularly those handling untrusted data inputs from external sources. Additionally, system administrators should implement monitoring for unusual application behavior patterns that might indicate exploitation attempts and consider implementing additional input validation layers as defensive measures.
This vulnerability aligns with ATT&CK technique T1203 - Exploitation for Client Execution, where attackers leverage library vulnerabilities to cause application instability. The issue also demonstrates how common cryptographic operations can become security risks when proper input sanitization is not implemented. Security teams should conduct comprehensive vulnerability assessments to identify all systems using affected SDK versions and ensure proper patch management protocols are in place to prevent similar issues from occurring in other components of the software stack.