AWS API MCP Server Security Policy Bypass via Incorrect Operation Name Normalization

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-125271
StatePUBLISHED
AssignerAMZN
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-10 17:17:28 UTC
Updated2026-11-10 17:17:28 UTC
DescriptionIncorrect 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.

Risk And Classification

Primary CVSS: v4.0 8.5 HIGH from ff89ba41-3aa1-4d27-914a-91399e9639e5

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

Problem Types: CWE-863 | CWE-1025 | CWE-1025 CWE-1025 Comparison using wrong factors | CWE-863 CWE-863 Incorrect authorization

VersionSourceTypeScoreSeverityVector
4.0ff89ba41-3aa1-4d27-914a-91399e9639e5Secondary8.5HIGHCVSS: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/C...
4.0CNACVSS8.5HIGHCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
3.1ff89ba41-3aa1-4d27-914a-91399e9639e5Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
3.1CNACVSS7.8HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS v4.0 Breakdown

Attack Vector
Local
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
Passive
Confidentiality
High
Integrity
High
Availability
High
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA AWS Aws-api-mcp-server affected 0.2.13 1.5.1 custom Not specified

References

ReferenceSourceLinkTags
aws.amazon.com/security/security-bulletins/2026-176-aws ff89ba41-3aa1-4d27-914a-91399e9639e5 aws.amazon.com
github.com/awslabs/mcp/security/advisories/GHSA-4wq9-grf3-qg2p ff89ba41-3aa1-4d27-914a-91399e9639e5 github.com
pypi.org/project/awslabs.aws-api-mcp-server/1.5.1 ff89ba41-3aa1-4d27-914a-91399e9639e5 pypi.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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