QnABot on AWS EUVD-2026-93985

Exploitation requires that the OPTIONAL q-business-lambda-hook sample stack has been separately and manually deployed on top of QnABot on AWS 7.0.0 through 7.4.5 - it is not installed by default, and customers who never deployed the sample are unaffected. The attacker must be an authenticated remote user (CVSS PR:L) with access to the hook's request path. The principal limiting factors are: (1) the optional, manually-deployed nature of the vulnerable component, (2) the authentication requirement, and (3) impact scoped to S3 object read (confidentiality only) within the deploying AWS account. Note that remediation requires updating the QnABot stack to 7.4.6+ AND redeploying the hook sample stack; updating QnABot alone does not apply the fix.

This is a moderate, conditional risk rather than a widespread emergency. The CVSS 4.0 vector (AV:N/AC:L/PR:L/UI:N/VC:H) describes a network-reachable, low-complexity authorization bypass (CWE-639, IDOR via user-controlled key) that an already-authenticated user can trigger to read arbitrary S3 objects, with high confidentiality impact but no integrity or availability impact - consistent with the 7.1 score. The single most important mitigating signal is NOT in the CVSS metrics: the flaw exists only in an OPTIONAL sample Lambda hook (q-business-lambda-hook) that must be manually and separately deployed, so the real-world exposed population is a subset of an already-niche AWS solution. No EPSS score, no KEV listing, and no POC were provided in the input; exploitation status is therefore 'no public exploit identified at time of analysis.' PR:L confirms an authenticated attacker is required, which further narrows risk to environments exposing the hook to semi-trusted users. Net: credible and worth patching for the specific deployments that run the optional hook, but this is not a mass-exploitation candidate. Note a data caveat - the linked AWS advisory is a staging/marketing URL (staging.prod.website.marketing.aws.dev), so verify the final published bulletin.

An organization has manually deployed the optional Amazon Q Business Lambda hook sample alongside QnABot on AWS (7.0.0-7.4.5). An authenticated user of the chatbot manipulates a user-controlled key parameter handled by the hook to reference S3 object keys they are not authorized to access, and the hook returns those arbitrary objects from the deploying AWS account. No public exploit code was identified in the provided data, but the low attack complexity (AC:L) makes manual exploitation straightforward once the hook is reachable.