CVE-2026-19643: Out-of-bounds read in the Base64 decoder in Amazon aws-sdk-cpp on signed-char platforms

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-12 · updated 2026-10-23
Weakness: CWE-125

Description

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.

Affected products

aws-sdk-cpp: before 1.11.862 — fixed in 1.11.862

How to fix

Upgrade to a fixed version: aws-sdk-cpp 1.11.862. Check the vendor advisory for mitigations.

References

https://aws.amazon.com/security/security-bulletins/2026-080-aws/
https://github.com/aws/aws-sdk-cpp/releases/tag/1.11.862
https://github.com/aws/aws-sdk-cpp/security/advisories/GHSA-mxm9-xpf9-x66x

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