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VulnerabilityPublished Updated

CVE-2026-89020: MikroTik RouterOS · Stack-based Buffer Overflow

Affects MikroTik RouterOSSource CVE Database V5

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Not known to be exploited · CVSS 5.3 Medium : upgrade to 7.24.2 or 7.23.4 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score
5.3Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 7.24.2, 7.23.4
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade MikroTik RouterOS to 7.24.2 or 7.23.4.

Affected software

ProductAffectedFixed in
MikroTikRouterOSAffected
  • >=7.24.0 <7.24.2
Fixed in
  • 7.24.2
MikroTikRouterOSAffected
  • <7.23.4
Fixed in
  • 7.23.4

AI-suggested

If you cannot patch yet, restrict access to authenticated users and monitor usage of the /tool fetch command with tftp:// URLs to mitigate potential exploitation.

Description

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.

References

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