CVE-2026-19642 in aws-sdk-cpp
Summary
by MITRE • 08/12/2026
An out-of-bounds write issue in the Base64 decoder in Amazon aws-sdk-cpp before 1.11.862 might allow a remote authenticated user to cause a crash or heap memory corruption in 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 write condition within the Base64 decoding implementation of the AWS SDK for C++ library. The flaw occurs when processing specially crafted Base64-encoded input data that exceeds expected buffer boundaries during the decoding process. Such vulnerabilities fall under the common weakness enumeration CWE-787, which specifically addresses out-of-bounds write conditions that can lead to arbitrary code execution or system instability. The vulnerability affects versions prior to 1.11.862 and presents a remote attack surface for authenticated users who can submit malicious Base64 input to applications utilizing the affected library.
The technical implementation of this issue stems from inadequate bounds checking within the Base64 decoding algorithm. When the decoder processes input data, it fails to properly validate array indices or buffer limits, allowing write operations to occur beyond allocated memory boundaries. This type of vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1059.007 for execution through scripting and T1203 for exploitation of memory corruption vulnerabilities. Applications that rely on the AWS SDK for C++ for processing user-supplied Base64 data become susceptible to crashes, heap corruption, or potentially more severe consequences depending on system configuration and memory layout.
The operational impact of this vulnerability extends beyond simple application instability, as it can affect any service or application that utilizes the affected AWS SDK components for Base64 processing. This includes web applications, backend services, mobile applications, and enterprise systems that may process Base64-encoded data from external sources without proper validation. The authentication requirement lowers the barrier to exploitation compared to fully remote attacks but still requires legitimate credentials to access the system. Attackers can leverage this vulnerability to cause denial of service conditions or potentially escalate privileges if memory corruption leads to code execution opportunities.
The remediation strategy focuses on upgrading to version 1.11.862, which includes proper bounds checking and input validation mechanisms within the Base64 decoding functions. This update addresses the root cause by implementing robust boundary validation that prevents write operations beyond allocated buffers. Organizations should conduct thorough testing of their applications after applying this patch to ensure compatibility and verify that no regression issues have been introduced. Additional mitigations may include input sanitization layers, runtime monitoring for abnormal memory access patterns, and regular security assessments of third-party libraries to identify similar vulnerabilities across the software supply chain. The vulnerability highlights the importance of maintaining up-to-date dependencies and implementing proper security controls in software development lifecycle practices that align with industry standards including OWASP Top Ten and NIST guidelines for secure coding practices.