CVE-2026-18830: CWE-1287 Improper validation of specified type of input in AWS Amazon Bedrock AgentCore harness
Insufficient input validation in Amazon Bedrock AgentCore harness might allow an authenticated remote user to execute configured tools bypassing model invocation and security controls via crafted content blocks in conversation messages. AWS has addressed this issue. No customer action is required.
AI Analysis
Technical Summary
This vulnerability (CVE-2026-18830) in the Amazon Bedrock AgentCore harness InvokeHarness API involves improper validation of input types (CWE-1287). Specifically, when the last message in an InvokeHarness request includes a tool-use content block, the agent event loop may dispatch the named tool directly, bypassing the intended model mediation and associated security controls. The scope of impact is limited to the tools configured on the harness, restricting unauthorized tool execution to those available. The vulnerability affects versions prior to July 31, 2026. AWS has acknowledged the issue and manages remediation for this cloud-hosted service.
Potential Impact
An authenticated user can bypass model invocation and security controls to execute configured tools directly on the Amazon Bedrock AgentCore harness. The impact is confined to the tools configured on the harness, so a harness with no configured tools cannot be exploited, and those with restricted tool sets limit the scope of potential misuse. The vulnerability does not affect availability but has high confidentiality and integrity impact as per CVSS 8.1.
Mitigation Recommendations
AWS manages remediation for this cloud-hosted service and has released a security bulletin (https://aws.amazon.com/security/security-bulletins/2026-073-aws/) with the latest guidance. Users should ensure they are using versions of the Amazon Bedrock AgentCore harness InvokeHarness API updated on or after July 31, 2026, when the fix was applied. Check the vendor advisory for the most current remediation instructions.
CVE-2026-18830: CWE-1287 Improper validation of specified type of input in AWS Amazon Bedrock AgentCore harness
Description
Insufficient input validation in Amazon Bedrock AgentCore harness might allow an authenticated remote user to execute configured tools bypassing model invocation and security controls via crafted content blocks in conversation messages. AWS has addressed this issue. No customer action is required.
CVSS v3.1
Score 8.1high
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability (CVE-2026-18830) in the Amazon Bedrock AgentCore harness InvokeHarness API involves improper validation of input types (CWE-1287). Specifically, when the last message in an InvokeHarness request includes a tool-use content block, the agent event loop may dispatch the named tool directly, bypassing the intended model mediation and associated security controls. The scope of impact is limited to the tools configured on the harness, restricting unauthorized tool execution to those available. The vulnerability affects versions prior to July 31, 2026. AWS has acknowledged the issue and manages remediation for this cloud-hosted service.
Potential Impact
An authenticated user can bypass model invocation and security controls to execute configured tools directly on the Amazon Bedrock AgentCore harness. The impact is confined to the tools configured on the harness, so a harness with no configured tools cannot be exploited, and those with restricted tool sets limit the scope of potential misuse. The vulnerability does not affect availability but has high confidentiality and integrity impact as per CVSS 8.1.
Mitigation Recommendations
AWS manages remediation for this cloud-hosted service and has released a security bulletin (https://aws.amazon.com/security/security-bulletins/2026-073-aws/) with the latest guidance. Users should ensure they are using versions of the Amazon Bedrock AgentCore harness InvokeHarness API updated on or after July 31, 2026, when the fix was applied. Check the vendor advisory for the most current remediation instructions.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- AMZN
- Date Reserved
- 2026-08-04T14:11:16.899Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
- Is Cloud Service
- true
- Vendor Advisory Urls
- [{"url":"https://aws.amazon.com/security/security-bulletins/2026-073-aws/","vendor":"AWS"}]
Threat ID: 6a7227ffbf8831d53935a8d4
Added to database: 08/04/2026, 17:57:19 UTC
Last enriched: 08/04/2026, 17:57:42 UTC
Last updated: 08/04/2026, 20:22:16 UTC
Views: 5
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