CVE-2026-89020
MikroTik RouterOS Stack Buffer Overflow via TFTP URL Path
MEDIUM 5.3EPSS 0.5%
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 that allows authenticated users to crash the mtget worker process by supplying a URL path of 507 bytes or more to the /tool fetch command; the first write outside the 528-byte buffer occurs at 505 bytes. Attackers can trigger the overflow by issuing a fetch command with a crafted tftp:// URL path, which causes an unbounded rep movsb instruction to overwrite saved registers at a deterministic offset, crashing the process without requiring a reachable TFTP server or elevated privileges beyond read-only group membership.
- Affected
- MikroTik · RouterOS
- CVSS v4.0 VulnCheck
- 5.3 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - CVSS v3.1 VulnCheck
- 4.3 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L - EPSS
- 0.49% chance of exploitation in the next 30 days, 42nd percentile
- Published
- 2026-09-14
- Updated
- 2026-10-01
Proof-of-concept exploits (1)
- davtur19/PoC-CVE-2026-89020-PrivEscRepo stars 0★ · pushed 2026-10-31 · find archive
CVE references
- https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801PATCH
- https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800PATCH
- https://www.vulncheck.com/advisories/mikrotik-routeros-stack-buffer-overflow-via-tftp-url…ADVISORY