CVE-2026-4269
Improper S3 ownership verification in Bedrock AgentCore Starter Toolkit
A missing S3 ownership verification in the Bedrock AgentCore Starter Toolkit before version v0.1.13 may allow a remote actor to inject code during the build process, leading to code execution in the AgentCore Runtime. This issue only affects users of the Bedrock AgentCore Starter Toolkit before version v0.1.13 who build or have built the Toolkit after September 24, 2025. Any users on a version >=v0.1.13, and any users on previous versions who built the toolkit before September 24, 2025 are not affected.
To remediate this issue, customers should upgrade to version v0.1.13.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- None
- User interaction
- Passive
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Improper S3 ownership verification in Bedrock AgentCore Starter Toolkit
A missing S3 ownership verification in the Bedrock AgentCore Starter Toolkit before version v0.1.13 may allow a remote actor to inject code during the build process, leading to code execution in the AgentCore Runtime. This issue only affects users of the Bedrock AgentCore Starter Toolkit before version v0.1.13 who build or have built the Toolkit after September 24, 2025. Any users on a version >=v0.1.13, and any users on previous versions who built the toolkit before September 24, 2025 are not affected.
To remediate this issue, customers should upgrade to version v0.1.13.
- Record
CVE-2026-4269- CVSS 4.0
- 5.8 Medium
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Weakness
- CWE-340, CWE-283
- Updated
- 2026-11-02
EUVDEUVD-2026-12490
A missing S3 ownership verification in the Bedrock AgentCore Starter Toolkit before version v0.1.13 may allow a remote actor to inject code during the build process, leading to code execution in the AgentCore Runtime. This issue only affects users of the Bedrock AgentCore Starter Toolkit before version v0.1.13 who build or have built the Toolkit after September 24, 2025. Any users on a version >=v0.1.13, and any users on previous versions who built the toolkit before September 24, 2025 are not affected.
To remediate this issue, customers should upgrade to version v0.1.13.
- Record
EUVD-2026-12490- CVSS 4.0
- 5.8 Medium
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-xfhr-q72q-jcrj
Improper S3 ownership verification in Bedrock AgentCore Starter Toolkit
Summary
An issue has been identified in the Bedrock AgentCore Starter Toolkit versions prior to v0.1.13 that may allow a remote actor to inject code during the build process, leading to code execution in the AgentCore Runtime.
Impact
A remote actor could inject code during the build process, leading to code execution in the AgentCore Runtime and a complete loss of confidentiality, integrity, and availability of the affected AgentCore resource.
Impacted versions: All versions of Bedrock AgentCore Starter Toolkit versions before v0.1.13. This issue only affects users of the Bedrock AgentCore Starter Toolkit before version v0.1.13 who build the Toolkit after September 24, 2025. Any users on a version >=v0.1.13, and any users on previous versions who built the toolkit before September 24, 2025 date are not affected.
Patches
This issue has been addressed in version v0.1.13. AWS recommends upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.
Workarounds
N/A
References
If you have any questions or comments about this advisory, contact [AWS/Amazon] Security via our vulnerability reporting page or directly via email to [email protected]. Please do not create a public GitHub issue.
- Record
GHSA-xfhr-q72q-jcrj- CVSS 4.0
- 5.8 Medium
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Weakness
- CWE-283, CWE-340
- Updated
- 2026-11-02
NVD
A missing S3 ownership verification in the Bedrock AgentCore Starter Toolkit before version v0.1.13 may allow a remote actor to inject code during the build process, leading to code execution in the AgentCore Runtime. This issue only affects users of the Bedrock AgentCore Starter Toolkit before version v0.1.13 who build or have built the Toolkit after September 24, 2025. Any users on a version >=v0.1.13, and any users on previous versions who built the toolkit before September 24, 2025 are not affected.
To remediate this issue, customers should upgrade to version v0.1.13.
- Record
CVE-2026-4269- CVSS 4.0
- 5.8 Medium
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Weakness
- CWE-283, CWE-340
- Updated
- 2026-11-02
OSV
Improper S3 ownership verification in Bedrock AgentCore Starter Toolkit
A missing S3 ownership verification in the Bedrock AgentCore Starter Toolkit before version v0.1.13 may allow a remote actor to inject code during the build process, leading to code execution in the AgentCore Runtime. This issue only affects users of the Bedrock AgentCore Starter Toolkit before version v0.1.13 who build or have built the Toolkit after September 24, 2025. Any users on a version >=v0.1.13, and any users on previous versions who built the toolkit before September 24, 2025 are not affected.
To remediate this issue, customers should upgrade to version v0.1.13.
- Record
CVE-2026-4269- CVSS 4.0
- 5.8 Medium
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H - Weakness
- CWE-283, CWE-340
- Updated
- 2026-11-02
OSVGHSA-xfhr-q72q-jcrj
Improper S3 ownership verification in Bedrock AgentCore Starter Toolkit
Summary
An issue has been identified in the Bedrock AgentCore Starter Toolkit versions prior to v0.1.13 that may allow a remote actor to inject code during the build process, leading to code execution in the AgentCore Runtime.
Impact
A remote actor could inject code during the build process, leading to code execution in the AgentCore Runtime and a complete loss of confidentiality, integrity, and availability of the affected AgentCore resource.
Impacted versions: All versions of Bedrock AgentCore Starter Toolkit versions before v0.1.13. This issue only affects users of the Bedrock AgentCore Starter Toolkit before version v0.1.13 who build the Toolkit after September 24, 2025. Any users on a version >=v0.1.13, and any users on previous versions who built the toolkit before September 24, 2025 date are not affected.
Patches
This issue has been addressed in version v0.1.13. AWS recommends upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.
Workarounds
N/A
References
If you have any questions or comments about this advisory, contact [AWS/Amazon] Security via our vulnerability reporting page or directly via email to [email protected]. Please do not create a public GitHub issue.
- Record
GHSA-xfhr-q72q-jcrj- CVSS 4.0
- 5.8 Medium
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Weakness
- CWE-283, CWE-340
- Updated
- 2026-11-02
OSVPYSEC-2026-2396
Improper S3 ownership verification in Bedrock AgentCore Starter Toolkit
Summary
An issue has been identified in the Bedrock AgentCore Starter Toolkit versions prior to v0.1.13 that may allow a remote actor to inject code during the build process, leading to code execution in the AgentCore Runtime.
Impact
A remote actor could inject code during the build process, leading to code execution in the AgentCore Runtime and a complete loss of confidentiality, integrity, and availability of the affected AgentCore resource.
Impacted versions: All versions of Bedrock AgentCore Starter Toolkit versions before v0.1.13. This issue only affects users of the Bedrock AgentCore Starter Toolkit before version v0.1.13 who build the Toolkit after September 24, 2025. Any users on a version >=v0.1.13, and any users on previous versions who built the toolkit before September 24, 2025 date are not affected.
Patches
This issue has been addressed in version v0.1.13. AWS recommends upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.
Workarounds
N/A
References
If you have any questions or comments about this advisory, contact [AWS/Amazon] Security via our vulnerability reporting page or directly via email to [email protected]. Please do not create a public GitHub issue.
- Record
PYSEC-2026-2396- CVSS 4.0
- 5.8 Medium
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
bedrock-agentcore-starter-toolkitPyPI |
before 0.1.13 | 0.1.13 |
bedrock-agentcore-starter-toolkitPyPI |
before 0.1.13, plus listed versions 0.0.10.1.00.1.10.1.100.1.11 Show 9 moreShow less0.1.120.1.20.1.30.1.40.1.50.1.60.1.70.1.80.1.9 |
0.1.13 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-4269 is a medium vulnerability (CVSS 5.8) in Amazon Bedrock Agentcore Starter Toolkit, published March 16, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.26%, the 17th percentile. Fixed in bedrock-agentcore-starter-toolkit 0.1.13.
References
github.com/aws/bedrock-agentcore-starter-toolkit/releases/tag/v0.1.13
aws.amazon.com/security/security-bulletins/2026-008-AWS
nvd.nist.gov/vuln/detail/CVE-2026-4269
pypi.org/project/bedrock-agentcore-starter-toolkit