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CVE-2026-125271

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

Products / packages aws-api-mcp-server

Published

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Severity and exploitation

Not in CISA KEV

KEV coverage does not rule out exploitation.

KEV checked 15/11/2026, 02:35:33 UTC
AMZN · CVSS:3.1 · 7.8
Assessment vectorCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
AMZN · CVSS:4.0 · 8.5
Assessment vectorCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
The headline uses the highest imported catalog score. Assessments can differ by source and CVSS version.

Severity

high8.5

CVSS measures technical severity, not the likelihood of an attack.

Known exploitation

Not listed in the checked CISA KEV catalog

Absence from CISA KEV does not rule out attacks.

Public exploit

Not established by this record

Missing evidence does not mean no public exploit exists.

Remediation

Fix status not established

No structured fix or guidance is available here. Check the latest publisher advisory.

What this means

The AWS API MCP Server before version 1.5.1 has a security policy bypass vulnerability due to incorrect operation name normalization, potentially allowing an actor to execute denied AWS API operations. The weakness is caused by comparison using wrong factors and incorrect authorization. Affected versions include 0.2.13.

Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.

Attack conditions

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.

Excerpt from the original source description below.

Review supporting sources →

Affected versions

Check the exact model, release, and any platform requirements against your installation.

AWS · AMZN

aws-api-mcp-server

1 range
AMZN version evidence

Compare with this publisher’s ranges. This does not inspect your installation.

affected

0.2.13 → before 1.5.1

custom versions

unaffected

unknown

Other versions: unaffected

Automatic dependency matching is unavailable for this record. Use the product evidence and publisher’s instructions to check your installation.

What to do

Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.

No structured fix or remediation guidance is available here. Check the full source description and vendor’s latest advisory for a patch or workaround; do not assume another version is safe.

cve.new guidance unless attributed to a publisher. This page does not inspect your installation.

Public exploit evidence

No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.

Original source description

Read the full publisher description

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.

References

3 sources
pypi.org/project/awslabs.aws-api-mcp-server/1.5.1/
PatchAMZN
aws.amazon.com/security/security-bulletins/2026-176-aws/
Vendor advisoryAMZN
awslabs/mcp · security/advisories/GHSA-4wq9-grf3-qg2p
Security advisoryAMZN

Inside the record

Evidence available

Package identity · not supplied
Version evidence
Remediation guidance · not supplied
Weakness classification
Additional publishers · not supplied

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-125271

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-1025 ↗

CWE-1025 Comparison using wrong factors

AMZN

Related →
CWE-863 ↗

CWE-863 Incorrect authorization

AMZN

Related →

Environment requirements

These conditions apply together as specified by the publisher. A matching product name alone does not establish exposure.

AMZN · platform conditions

Any condition may hold

Any condition may hold

Vulnerable product

cpe:2.3:a:aws:aws-api-mcp-server:*:*:*:*:*:*:*:*

From (inclusive): 0.2.13

Before: 1.5.1

Applicability preview
[
  {
    "operator": "OR",
    "nodes": [
      {
        "operator": "OR",
        "negate": false,
        "cpeMatch": [
          {
            "vulnerable": true,
            "criteria": "cpe:2.3:a:aws:aws-api-mcp-server:*:*:*:*:*:*:*:*",
            "versionStartIncluding": "0.2.13",
            "versionEndExcluding": "1.5.1"
          }
        ]
      }
    ]
  }
]
Contributing organizations · 1
AMZN

Assigning organization

2026-11-10

Timeline

All times UTC

  1. Advisory published

    Publication date supplied by the source.

  2. Source updated

    Latest modification date supplied by the source.

  3. Last imported by cve.new

    Latest catalog import, not the date we first saw this advisory.

What changed

Follow changes
  1. CVE · CVE-2026-125271

    Observed 2026-11-10T16:45:54.905Z · upstream updated 2026-11-10T16:35:38.381Z

    References changed

    before

    [
  "https://pypi.org/project/awslabs.aws-api-mcp-server/1.5.1/",
  "https://aws.amazon.com/security/security-bulletins/2026-176-aws/"
]

    after

    [
  "https://pypi.org/project/awslabs.aws-api-mcp-server/1.5.1/",
  "https://aws.amazon.com/security/security-bulletins/2026-176-aws/",
  "https://github.com/awslabs/mcp/security/advisories/GHSA-4wq9-grf3-qg2p"
]

Large field values are marked as truncated previews. Original source snapshots remain retained.

Showing up to 50 most recent observed changes.