Overview
CVE-2025-7623 describes a stack-based buffer overflow vulnerability found in the SMASH-CLP (Systems Management Architecture for Server Hardware Command Line Protocol) shell of Supermicro Baseboard Management Controllers (BMCs). Successful exploitation of this vulnerability allows an authenticated attacker with SSH access to the BMC to achieve arbitrary code execution on the BMC’s firmware operating system.
Technical Details
The vulnerability lies within the SMASH-CLP shell implementation. A specially crafted SMASH command, exceeding 260 bytes, can overflow a stack buffer. This overflow allows an attacker to overwrite the return address and registers on the stack. By carefully crafting the overflow, the attacker can redirect the execution flow to arbitrary code, effectively gaining control of the BMC’s firmware OS.
The attacker needs valid SSH credentials to the BMC to exploit this vulnerability. This implies that an initial level of access is required, making it an authenticated vulnerability.
Example of a potentially malicious command structure (Illustrative):
SMASH> [Overflow data exceeding 260 bytes]
CVSS Analysis
The Common Vulnerability Scoring System (CVSS) score for CVE-2025-7623 is 5.4, categorized as MEDIUM severity.
- CVSS Score: 5.4
- Vector: AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L
- Explanation: This score reflects that the vulnerability can be exploited over the network (AV:N) with low attack complexity (AC:L), but requires high privileges (PR:H) – specifically SSH access to the BMC. There is no user interaction (UI:N) required. The scope is unchanged (S:U). The confidentiality, integrity, and availability impacts are low (C:L/I:L/A:L).
Possible Impact
Exploitation of CVE-2025-7623 can have significant consequences:
- Arbitrary Code Execution: The attacker gains the ability to execute arbitrary code on the BMC, allowing them to install malware, modify system configurations, or potentially brick the device.
- Privilege Escalation: Even if the initial SSH access is limited, successful exploitation grants full control over the BMC.
- Lateral Movement: A compromised BMC can be used as a pivot point to attack other systems within the network, especially if the BMC has access to sensitive internal resources.
- Denial of Service: The attacker can intentionally crash or destabilize the BMC, leading to a denial-of-service condition.
- Data Exfiltration: If the BMC manages or has access to sensitive data (e.g., server logs, system credentials), the attacker can exfiltrate this information.
Mitigation or Patch Steps
To mitigate the risk of CVE-2025-7623, apply the following steps:
- Apply the Patch: The primary mitigation is to update the BMC firmware to the latest version provided by Supermicro. Refer to the Supermicro security advisory for the specific firmware version that addresses this vulnerability.
- Restrict BMC Access: Limit access to the BMC network. Place the BMC on a separate, isolated network segment and restrict access based on the principle of least privilege.
- Strong Authentication: Enforce strong passwords for BMC accounts and consider implementing multi-factor authentication (MFA) for SSH access.
- Monitor BMC Activity: Monitor BMC logs for suspicious activity, such as unusual command execution or unauthorized access attempts.
- Disable Unnecessary Services: If the SMASH-CLP shell is not required, consider disabling it to reduce the attack surface.
