Executive brief
MikroTik RouterOS includes a file sharing daemon (SMB) that allows network-attached devices to share files and printers. A flaw in the SMB1 protocol handler permits remote attackers to send a malformed file-sharing request that triggers a memory corruption vulnerability, potentially crashing the router or allowing arbitrary code execution. This affects routers running RouterOS versions before 7.24.
Technical details
The vulnerability is a heap-based buffer overflow caused by integer underflow in the SMB1 SessionSetupAndX handler. When processing a crafted SMB1 request with a malicious uniPwdLen field value, the daemon fails to properly validate the value, leading to integer wraparound. This underflowed value is then used as the length parameter in a memory copy operation, causing data to be written beyond the bounds of an allocated heap buffer. The attack is network-reachable and requires no authentication or user interaction. An attacker can corrupt adjacent heap memory, potentially achieving denial of service or code execution. The vulnerability was fixed in RouterOS version 7.24 released in August 2026.
Affected products
- MikroTik RouterOS before 7.24 (including 6.49.18 and earlier, 7.0.0 through 7.11.2)
Timeline
- 2026-09-16: disclosed
- 2026-08-14: patched: RouterOS 7.24 released