How severe is CVE-2026-4269?

CVE-2026-4269 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-4269 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-4269?

CVE-2026-4269 affects Amazon Bedrock Agentcore Starter Toolkit. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-4269?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-4269 have an EU (EUVD) identifier?

Yes. CVE-2026-4269 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12490.

When was CVE-2026-4269 published?

CVE-2026-4269 was published on 2026-03-16 and last updated on 2026-06-17.

CVE-2026-4269

CVE-2026-4269 is a high-severity vulnerability in Amazon Bedrock Agentcore Starter Toolkit with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-283.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 5.8
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-12490
Weakness: CWE-283
Affected product: Amazon Bedrock Agentcore Starter Toolkit
Published: 2026-03-16
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2026-4269?: 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.
How severe is CVE-2026-4269?: CVE-2026-4269 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-4269 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-4269?: CVE-2026-4269 affects Amazon Bedrock Agentcore Starter Toolkit. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-4269?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-4269 have an EU (EUVD) identifier?: Yes. CVE-2026-4269 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12490.
When was CVE-2026-4269 published?: CVE-2026-4269 was published on 2026-03-16 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:amazon:bedrock_agentcore_starter_toolkit:*:*:*:*:*:python:*:*

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