CVE-2026-125271
Incorrect normalization of operation names in the custom security policy enforcement in awslabs aws-api-mcp-server before 1.5.1 might allow an actor to execute AWS API operations across AWS services that the operator's security policy was configured to deny or require elicitation for, via calls to operations whose names contain consecutive capital letters. To remediate this issue, users should upgrade to version 1.5.1.
Executive briefing
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Evidence confidence: Not assessed Evidence-derived, not an exploitability verdict
Severity & attack characteristics
CVSS vector:CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/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
Technical explanation & impact
Technical root-cause details are not available in the current source record.
Assess the impact using the published CVSS metrics and the affected vendor component.
Affected products and versions
NVD has not supplied machine-readable vulnerable CPE product/version entries for this CVE. This is an information gap, not proof that no products are affected. Check the vendor advisory references below.
Remediation & validation
- Identify exposure by comparing the affected product and version ranges with your asset inventory, SBOM and externally exposed services.
- Review the linked vendor security advisory or patch notes. Upgrade to a vendor-confirmed fixed release; do not infer a fixed version from the CVE description.
- Until patched, consider restricting network access or disabling the affected feature where operationally safe. These are temporary controls, not a substitute for a vendor fix.
- Validate the remediation with a version check and vulnerability rescan, then retain change evidence.
No fixed version is displayed unless it is explicitly established by a vendor advisory. Follow the vendor's release notes for exact product and branch applicability.
Vendor advisories, patches & exploit references
- https://aws.amazon.com/security/security-bulletins/2026-176-aws/ REFERENCE ff89ba41-3aa1-4d27-914a-91399e9639e5
- https://github.com/awslabs/mcp/security/advisories/GHSA-4wq9-grf3-qg2p VENDOR ff89ba41-3aa1-4d27-914a-91399e9639e5
- https://pypi.org/project/awslabs.aws-api-mcp-server/1.5.1/ REFERENCE ff89ba41-3aa1-4d27-914a-91399e9639e5