CVE-2023-34108
Manipulation of Internal Dovecot Variables in mailcow via crafted Passwords
mailcow is a mail server suite based on Dovecot, Postfix and other open source software, that provides a modern web UI for user/server administration. A vulnerability has been discovered in mailcow which allows an attacker to manipulate internal Dovecot variables by using specially crafted passwords during the authentication process. The issue arises from the behavior of the passwd-verify.lua script, which is responsible for verifying user passwords during login attempts. Upon a successful login, the script returns a response in the format of "password=<valid-password>", indicating the successful authentication. By crafting a password with additional key-value pairs appended to it, an attacker can manipulate the returned string and influence the internal behavior of Dovecot. For example, using the password "123 mail_crypt_save_version=0" would cause the passwd-verify.lua script to return the string "password=123 mail_crypt_save_version=0". Consequently, Dovecot will interpret this string and set the internal variables accordingly, leading to unintended consequences. This vulnerability can be exploited by an authenticated attacker who has the ability to set their own password. Successful exploitation of this vulnerability could result in unauthorized access to user accounts, bypassing security controls, or other malicious activities. This issue has been patched in version 2023-05a. Users are advised to upgrade. There are no known workarounds for this vulnerability.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
8.8
Manipulation of Internal Dovecot Variables in mailcow via crafted Passwords
mailcow is a mail server suite based on Dovecot, Postfix and other open source software, that provides a modern web UI for user/server administration. A vulnerability has been discovered in mailcow which allows an attacker to manipulate internal Dovecot variables by using specially crafted passwords during the authentication process. The issue arises from the behavior of the passwd-verify.lua script, which is responsible for verifying user passwords during login attempts. Upon a successful login, the script returns a response in the format of "password=<valid-password>", indicating the successful authentication. By crafting a password with additional key-value pairs appended to it, an attacker can manipulate the returned string and influence the internal behavior of Dovecot. For example, using the password "123 mail_crypt_save_version=0" would cause the passwd-verify.lua script to return the string "password=123 mail_crypt_save_version=0". Consequently, Dovecot will interpret this string and set the internal variables accordingly, leading to unintended consequences. This vulnerability can be exploited by an authenticated attacker who has the ability to set their own password. Successful exploitation of this vulnerability could result in unauthorized access to user accounts, bypassing security controls, or other malicious activities. This issue has been patched in version 2023-05a. Users are advised to upgrade. There are no known workarounds for this vulnerability.
- Record
CVE-2023-34108- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-78
- Updated
- 2026-11-02
EUVDEUVD-2023-38211
8.8
mailcow is a mail server suite based on Dovecot, Postfix and other open source software, that provides a modern web UI for user/server administration. A vulnerability has been discovered in mailcow which allows an attacker to manipulate internal Dovecot variables by using specially crafted passwords during the authentication process. The issue arises from the behavior of the passwd-verify.lua script, which is responsible for verifying user passwords during login attempts. Upon a successful login, the script returns a response in the format of "password=<valid-password>", indicating the successful authentication. By crafting a password with additional key-value pairs appended to it, an attacker can manipulate the returned string and influence the internal behavior of Dovecot. For example, using the password "123 mail_crypt_save_version=0" would cause the passwd-verify.lua script to return the string "password=123 mail_crypt_save_version=0". Consequently, Dovecot will interpret this string and set the internal variables accordingly, leading to unintended consequences. This vulnerability can be exploited by an authenticated attacker who has the ability to set their own password. Successful exploitation of this vulnerability could result in unauthorized access to user accounts, bypassing security controls, or other malicious activities. This issue has been patched in version 2023-05a. Users are advised to upgrade. There are no known workarounds for this vulnerability.
- Record
EUVD-2023-38211- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-03
NVD
8.8
mailcow is a mail server suite based on Dovecot, Postfix and other open source software, that provides a modern web UI for user/server administration. A vulnerability has been discovered in mailcow which allows an attacker to manipulate internal Dovecot variables by using specially crafted passwords during the authentication process. The issue arises from the behavior of the passwd-verify.lua script, which is responsible for verifying user passwords during login attempts. Upon a successful login, the script returns a response in the format of "password=<valid-password>", indicating the successful authentication. By crafting a password with additional key-value pairs appended to it, an attacker can manipulate the returned string and influence the internal behavior of Dovecot. For example, using the password "123 mail_crypt_save_version=0" would cause the passwd-verify.lua script to return the string "password=123 mail_crypt_save_version=0". Consequently, Dovecot will interpret this string and set the internal variables accordingly, leading to unintended consequences. This vulnerability can be exploited by an authenticated attacker who has the ability to set their own password. Successful exploitation of this vulnerability could result in unauthorized access to user accounts, bypassing security controls, or other malicious activities. This issue has been patched in version 2023-05a. Users are advised to upgrade. There are no known workarounds for this vulnerability.
- Record
CVE-2023-34108- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-78
- Updated
- 2026-11-02
OSV
8.8
Manipulation of Internal Dovecot Variables in mailcow via crafted Passwords
mailcow is a mail server suite based on Dovecot, Postfix and other open source software, that provides a modern web UI for user/server administration. A vulnerability has been discovered in mailcow which allows an attacker to manipulate internal Dovecot variables by using specially crafted passwords during the authentication process. The issue arises from the behavior of the passwd-verify.lua script, which is responsible for verifying user passwords during login attempts. Upon a successful login, the script returns a response in the format of "password=<valid-password>", indicating the successful authentication. By crafting a password with additional key-value pairs appended to it, an attacker can manipulate the returned string and influence the internal behavior of Dovecot. For example, using the password "123 mail_crypt_save_version=0" would cause the passwd-verify.lua script to return the string "password=123 mail_crypt_save_version=0". Consequently, Dovecot will interpret this string and set the internal variables accordingly, leading to unintended consequences. This vulnerability can be exploited by an authenticated attacker who has the ability to set their own password. Successful exploitation of this vulnerability could result in unauthorized access to user accounts, bypassing security controls, or other malicious activities. This issue has been patched in version 2023-05a. Users are advised to upgrade. There are no known workarounds for this vulnerability.
- Record
CVE-2023-34108- CVSS 3.1
- 8.8 High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-78
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE List, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2023-34108 is a high vulnerability (CVSS 8.8) in Mailcow Mailcow-dockerized, published June 7, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.98%, the 62nd percentile. No source names a fixed version.
References
github.com/mailcow/mailcow-dockerized/security/advisories/GHSA-mhh4-qchc-pv22
github.com/mailcow/mailcow-dockerized/commit/f80940efdccd393bf5fccec2886795372a38c445
github.com/VladimirBorisov/CVE_proposal/blob/main/MailcowUserPassword.md
github.com/CVEProject/cvelistV5/tree/main/cves/2023/34xxx/CVE-2023-34108.json
nvd.nist.gov/vuln/detail/CVE-2023-34108