SMTP falsely prefers IPv4 over IPv6 #855

New Issue

MrUnknownDE · 2026-04-06T00:05:27+02:00

MrUnknownDE commented

2026-04-06 00:05:27 +02:00

Originally created by @imp1sh on 11/5/2024

Vaultwarden Support String

Your environment (Generated via diagnostics page)

Vaultwarden version: v1.32.0-040e2a7b
Web-vault version: v2024.6.2c
OS/Arch: linux/x86_64
Running within a container: true (Base: Debian)
Environment settings overridden: true
Uses a reverse proxy: true
IP Header check: true (X-Real-IP)
Internet access: true
Internet access via a proxy: false
DNS Check: true
Browser/Server Time Check: false
Server/NTP Time Check: true
Domain Configuration Check: true
HTTPS Check: true
Database type: SQLite
Database version: 3.46.0
Clients used:
Reverse proxy and version:
Other relevant information:

Config (Generated via diagnostics page)

Show Running Config

Environment settings which are overridden: DOMAIN, SIGNUPS_ALLOWED, ADMIN_TOKEN, SMTP_HOST, SMTP_SECURITY, SMTP_PORT, SMTP_FROM, SMTP_USERNAME, SMTP_PASSWORD

{
  "_duo_akey": null,
  "_enable_duo": false,
  "_enable_email_2fa": false,
  "_enable_smtp": true,
  "_enable_yubico": true,
  "_icon_service_csp": "",
  "_icon_service_url": "",
  "_ip_header_enabled": true,
  "_max_note_size": 10000,
  "_smtp_img_src": "cid:",
  "admin_ratelimit_max_burst": 3,
  "admin_ratelimit_seconds": 300,
  "admin_session_lifetime": 20,
  "admin_token": "***",
  "allowed_iframe_ancestors": "",
  "attachments_folder": "data/attachments",
  "auth_request_purge_schedule": "30 * * * * *",
  "authenticator_disable_time_drift": false,
  "data_folder": "data",
  "database_conn_init": "",
  "database_max_conns": 10,
  "database_timeout": 30,
  "database_url": "***************",
  "db_connection_retries": 15,
  "disable_2fa_remember": false,
  "disable_admin_token": false,
  "disable_icon_download": false,
  "domain": "*****://*************",
  "domain_origin": "*****://*************",
  "domain_path": "",
  "domain_set": true,
  "duo_context_purge_schedule": "30 * * * * *",
  "duo_host": null,
  "duo_ikey": null,
  "duo_skey": null,
  "duo_use_iframe": false,
  "email_2fa_auto_fallback": false,
  "email_2fa_enforce_on_verified_invite": false,
  "email_attempts_limit": 3,
  "email_change_allowed": true,
  "email_expiration_time": 600,
  "email_token_size": 6,
  "emergency_access_allowed": true,
  "emergency_notification_reminder_schedule": "0 3 * * * *",
  "emergency_request_timeout_schedule": "0 7 * * * *",
  "enable_db_wal": true,
  "enable_websocket": true,
  "enforce_single_org_with_reset_pw_policy": false,
  "event_cleanup_schedule": "0 10 0 * * *",
  "events_days_retain": null,
  "experimental_client_feature_flags": "fido2-vault-credentials",
  "extended_logging": true,
  "helo_name": null,
  "hibp_api_key": null,
  "http_request_block_non_global_ips": true,
  "http_request_block_regex": null,
  "icon_blacklist_non_global_ips": true,
  "icon_blacklist_regex": null,
  "icon_cache_folder": "data/icon_cache",
  "icon_cache_negttl": 259200,
  "icon_cache_ttl": 2592000,
  "icon_download_timeout": 10,
  "icon_redirect_code": 302,
  "icon_service": "internal",
  "incomplete_2fa_schedule": "30 * * * * *",
  "incomplete_2fa_time_limit": 3,
  "increase_note_size_limit": false,
  "invitation_expiration_hours": 120,
  "invitation_org_name": "Vaultwarden",
  "invitations_allowed": true,
  "ip_header": "X-Real-IP",
  "job_poll_interval_ms": 30000,
  "log_file": null,
  "log_level": "info",
  "log_timestamp_format": "%Y-%m-%d %H:%M:%S.%3f",
  "login_ratelimit_max_burst": 10,
  "login_ratelimit_seconds": 60,
  "org_attachment_limit": null,
  "org_creation_users": "",
  "org_events_enabled": false,
  "org_groups_enabled": false,
  "password_hints_allowed": true,
  "password_iterations": 100000,
  "push_enabled": false,
  "push_identity_uri": "https://identity.bitwarden.com",
  "push_installation_id": "***",
  "push_installation_key": "***",
  "push_relay_uri": "https://push.bitwarden.com",
  "reload_templates": false,
  "require_device_email": false,
  "rsa_key_filename": "data/rsa_key",
  "send_purge_schedule": "0 5 * * * *",
  "sendmail_command": null,
  "sends_allowed": true,
  "sends_folder": "data/sends",
  "show_password_hint": false,
  "signups_allowed": false,
  "signups_domains_whitelist": "",
  "signups_verify": true,
  "signups_verify_resend_limit": 6,
  "signups_verify_resend_time": 3600,
  "smtp_accept_invalid_certs": false,
  "smtp_accept_invalid_hostnames": false,
  "smtp_auth_mechanism": null,
  "smtp_debug": false,
  "smtp_embed_images": true,
  "smtp_explicit_tls": null,
  "smtp_from": "********************",
  "smtp_from_name": "Vaultwarden - Password Tresor",
  "smtp_host": "********************",
  "smtp_password": "***",
  "smtp_port": 587,
  "smtp_security": "starttls",
  "smtp_ssl": true,
  "smtp_timeout": 15,
  "smtp_username": "*********************",
  "templates_folder": "data/templates",
  "tmp_folder": "data/tmp",
  "trash_auto_delete_days": null,
  "trash_purge_schedule": "0 5 0 * * *",
  "use_sendmail": false,
  "use_syslog": false,
  "user_attachment_limit": null,
  "user_send_limit": null,
  "web_vault_enabled": true,
  "web_vault_folder": "web-vault/",
  "yubico_client_id": null,
  "yubico_secret_key": null,
  "yubico_server": null
}

Vaultwarden Build Version

1.32.3-2f20ad86 (testing tag)

Deployment method

Official Container Image

Custom deployment method

No response

Reverse Proxy

nginx 1.22.1

Host/Server Operating System

Linux

Operating System Version

Debian 12

Clients

Web Vault

Client Version

Firefox 132.0

Steps To Reproduce

Configure SMTP settings with DNS name that both resolves IPv6 and IPv4 address.
As in RFC 6724 it is required that IPv6 is being preferred over IPv4.

Expected Result

Instead of trying to connect to the SMTP host via IPv4 first, it should prefer IPv6. BTW it's a GUA address, no ULA.

Actual Result

The application tries to connect via IPv4 first.

Logs

[2024-11-05 20:53:38.655][request][INFO] POST /admin/test/smtp
[2024-11-05 20:53:39.336][response][INFO] (test_smtp) POST /admin/test/smtp => 200 OK

Screenshots or Videos

No response

Additional Context

No response

*Originally created by @imp1sh on 11/5/2024* ### Vaultwarden Support String ### Your environment (Generated via diagnostics page) * Vaultwarden version: v1.32.0-040e2a7b * Web-vault version: v2024.6.2c * OS/Arch: linux/x86_64 * Running within a container: true (Base: Debian) * Environment settings overridden: true * Uses a reverse proxy: true * IP Header check: true (X-Real-IP) * Internet access: true * Internet access via a proxy: false * DNS Check: true * Browser/Server Time Check: false * Server/NTP Time Check: true * Domain Configuration Check: true * HTTPS Check: true * Database type: SQLite * Database version: 3.46.0 * Clients used: * Reverse proxy and version: * Other relevant information: ### Config (Generated via diagnostics page) <details><summary>Show Running Config</summary> **Environment settings which are overridden:** DOMAIN, SIGNUPS_ALLOWED, ADMIN_TOKEN, SMTP_HOST, SMTP_SECURITY, SMTP_PORT, SMTP_FROM, SMTP_USERNAME, SMTP_PASSWORD ```json { "_duo_akey": null, "_enable_duo": false, "_enable_email_2fa": false, "_enable_smtp": true, "_enable_yubico": true, "_icon_service_csp": "", "_icon_service_url": "", "_ip_header_enabled": true, "_max_note_size": 10000, "_smtp_img_src": "cid:", "admin_ratelimit_max_burst": 3, "admin_ratelimit_seconds": 300, "admin_session_lifetime": 20, "admin_token": "***", "allowed_iframe_ancestors": "", "attachments_folder": "data/attachments", "auth_request_purge_schedule": "30 * * * * *", "authenticator_disable_time_drift": false, "data_folder": "data", "database_conn_init": "", "database_max_conns": 10, "database_timeout": 30, "database_url": "***************", "db_connection_retries": 15, "disable_2fa_remember": false, "disable_admin_token": false, "disable_icon_download": false, "domain": "*****://*************", "domain_origin": "*****://*************", "domain_path": "", "domain_set": true, "duo_context_purge_schedule": "30 * * * * *", "duo_host": null, "duo_ikey": null, "duo_skey": null, "duo_use_iframe": false, "email_2fa_auto_fallback": false, "email_2fa_enforce_on_verified_invite": false, "email_attempts_limit": 3, "email_change_allowed": true, "email_expiration_time": 600, "email_token_size": 6, "emergency_access_allowed": true, "emergency_notification_reminder_schedule": "0 3 * * * *", "emergency_request_timeout_schedule": "0 7 * * * *", "enable_db_wal": true, "enable_websocket": true, "enforce_single_org_with_reset_pw_policy": false, "event_cleanup_schedule": "0 10 0 * * *", "events_days_retain": null, "experimental_client_feature_flags": "fido2-vault-credentials", "extended_logging": true, "helo_name": null, "hibp_api_key": null, "http_request_block_non_global_ips": true, "http_request_block_regex": null, "icon_blacklist_non_global_ips": true, "icon_blacklist_regex": null, "icon_cache_folder": "data/icon_cache", "icon_cache_negttl": 259200, "icon_cache_ttl": 2592000, "icon_download_timeout": 10, "icon_redirect_code": 302, "icon_service": "internal", "incomplete_2fa_schedule": "30 * * * * *", "incomplete_2fa_time_limit": 3, "increase_note_size_limit": false, "invitation_expiration_hours": 120, "invitation_org_name": "Vaultwarden", "invitations_allowed": true, "ip_header": "X-Real-IP", "job_poll_interval_ms": 30000, "log_file": null, "log_level": "info", "log_timestamp_format": "%Y-%m-%d %H:%M:%S.%3f", "login_ratelimit_max_burst": 10, "login_ratelimit_seconds": 60, "org_attachment_limit": null, "org_creation_users": "", "org_events_enabled": false, "org_groups_enabled": false, "password_hints_allowed": true, "password_iterations": 100000, "push_enabled": false, "push_identity_uri": "https://identity.bitwarden.com", "push_installation_id": "***", "push_installation_key": "***", "push_relay_uri": "https://push.bitwarden.com", "reload_templates": false, "require_device_email": false, "rsa_key_filename": "data/rsa_key", "send_purge_schedule": "0 5 * * * *", "sendmail_command": null, "sends_allowed": true, "sends_folder": "data/sends", "show_password_hint": false, "signups_allowed": false, "signups_domains_whitelist": "", "signups_verify": true, "signups_verify_resend_limit": 6, "signups_verify_resend_time": 3600, "smtp_accept_invalid_certs": false, "smtp_accept_invalid_hostnames": false, "smtp_auth_mechanism": null, "smtp_debug": false, "smtp_embed_images": true, "smtp_explicit_tls": null, "smtp_from": "********************", "smtp_from_name": "Vaultwarden - Password Tresor", "smtp_host": "********************", "smtp_password": "***", "smtp_port": 587, "smtp_security": "starttls", "smtp_ssl": true, "smtp_timeout": 15, "smtp_username": "*********************", "templates_folder": "data/templates", "tmp_folder": "data/tmp", "trash_auto_delete_days": null, "trash_purge_schedule": "0 5 0 * * *", "use_sendmail": false, "use_syslog": false, "user_attachment_limit": null, "user_send_limit": null, "web_vault_enabled": true, "web_vault_folder": "web-vault/", "yubico_client_id": null, "yubico_secret_key": null, "yubico_server": null } ``` </details> ### Vaultwarden Build Version 1.32.3-2f20ad86 (testing tag) ### Deployment method Official Container Image ### Custom deployment method _No response_ ### Reverse Proxy nginx 1.22.1 ### Host/Server Operating System Linux ### Operating System Version Debian 12 ### Clients Web Vault ### Client Version Firefox 132.0 ### Steps To Reproduce Configure SMTP settings with DNS name that both resolves IPv6 and IPv4 address. As in RFC 6724 it is required that IPv6 is being preferred over IPv4. ### Expected Result Instead of trying to connect to the SMTP host via IPv4 first, it should prefer IPv6. BTW it's a GUA address, no ULA. ### Actual Result The application tries to connect via IPv4 first. ### Logs ```text [2024-11-05 20:53:38.655][request][INFO] POST /admin/test/smtp [2024-11-05 20:53:39.336][response][INFO] (test_smtp) POST /admin/test/smtp => 200 OK ``` ### Screenshots or Videos _No response_ ### Additional Context _No response_

MrUnknownDE closed this issue

2026-04-06 00:05:27 +02:00

MrUnknownDE added the enhancement Third party Third party Third party Third party enhancement enhancement enhancement enhancement enhancement enhancement enhancement labels 2026-04-06 00:05:28 +02:00

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No Label Third party Third party Third party Third party enhancement enhancement enhancement enhancement enhancement enhancement enhancement enhancement

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Reference: github/vaultwarden#855