CVE-2026-89028
HighCVSS 7.5Summary
MikroTik RouterOS before 7.24 contains a heap memory corruption vulnerability in the userspace SMB daemon that allows remote attackers to corrupt adjacent heap memory by supplying a crafted uniPwdLen value in the SMB1 SessionSetupAndX handler. An attacker can send a malformed SMB1 request with a uniPwdLen field that triggers an integer underflow, causing the resulting value to be used as the copy length in a memory copy operation into a smaller heap buffer, corrupting adjacent heap memory.
Risk Assessment
A remote attacker can exploit the vulnerability to corrupt memory, potentially leading to arbitrary code execution or SMB service crash. This could result in full compromise of the router device and network.
Recommendation
Immediately update MikroTik RouterOS to version 7.24 or later. If updating is not possible, disable the SMB service or restrict access to it from untrusted networks.
Other vulnerabilities in MikroTik RouterOS
See all- CVE-2025-56566Unknown
MikroTik firmware 7.19.4 stores sensitive authentication credentials and network state in cleartext within non-volatile storage. An attacker with physical access to the device can extract this material from an SPI flash dump without authenticating and without knowing the administrative password.
- CVE-2024-27686High
Mikrotik RouterOS versions 6.40.5 through 6.49.10 (fixed in 7) allow a remote attacker to cause a device crash via crafted packet data to the SMB service on TCP port 445.
- CVE-2018-14847CriticalActively exploited
MikroTik RouterOS through 6.42 allows unauthenticated remote attackers to read arbitrary files and remote authenticated attackers to write arbitrary files due to a directory traversal vulnerability in the WinBox interface.
- CVE-2018-7445CriticalActively exploited
A buffer overflow was found in the MikroTik RouterOS SMB service when processing NetBIOS session request messages. A remote attacker with access to the service can exploit this vulnerability to gain code execution on the system, and the overflow occurs before authentication, so an unauthenticated remote attacker can exploit it.
- CVE-2026-89021Medium
MikroTik RouterOS before 7.24.2 contains a path traversal vulnerability in the container package OCI/tar image extraction, allowing attackers to write files outside the container root by supplying a crafted container image with symlinks. Attackers can achieve root-privileged file creation, directory creation, file deletion, and hardlink creation on the persistent data partition without starting the container.
- CVE-2026-89020Medium
MikroTik RouterOS before 7.23.4 (long-term) and 7.24.2 (stable) contains a stack-based buffer overflow vulnerability in the mtget binary's TFTP RRQ builder function, allowing authenticated users to crash the mtget worker process by supplying a URL path of 507 bytes or more to the /tool fetch command.
- CVE-2026-67278Medium
MikroTik RouterOS (7.x) accepts malformed RSA/PKCS#1 v1.5 signatures across RSA-based services, including TLS/X.509 certificate validation and SSH host-key authentication. Because the trust store includes an e=3 root CA, an attacker controlling or redirecting outbound TLS can use the root's public certificate to forge a trusted intermediate and issue certificates for arbitrary hostnames, enabling TLS server impersonation. This also undermines RSA-based SSH authentication.
- CVE-2026-14227Medium
A product with the MikroTik RouterOS API enabled is vulnerable to insufficient session expiration. Active sessions may retain their previous permission set after inactivity timeouts or user-group changes.
- CVE-2026-16347High
MikroTik RouterOS contains a weakness in its API authentication handling that lacks effective safeguards against excessive login attempts. The system does not enforce meaningful rate-limiting, account lockout, or source-based restrictions, allowing repeated authentication failures to proceed without defensive response. In some versions, a fixed per-connection delay is present, but it can be bypassed through concurrent sessions, resulting in continued high-volume attempts.
- CVE-2026-39042High
A vulnerability in MikroTik RouterOS versions 7.21.x before 7.21.4 and 7.22.x before 7.22.2 exists in the unflatten() function of the libumsg.so library. A remote attacker can exploit this flaw to cause a denial of service (DoS).
Original NVD description (English source)
MikroTik RouterOS before 7.24 contains a heap memory corruption vulnerability in the userspace SMB daemon that allows remote attackers to corrupt adjacent heap memory by supplying a crafted uniPwdLen value in the SMB1 SessionSetupAndX handler. An attacker can send a malformed SMB1 request with a uniPwdLen field that triggers an integer underflow, causing the resulting value to be used as the copy length in a memory copy operation into a smaller heap buffer, corrupting adjacent heap memory.