Vulnerability-Lookup

CVE-2026-89020 (GCVE-0-2026-89020)

Vulnerability from cvelistv5 – Published: 2026-09-14 18:02 – Updated: 2026-09-14 18:02

Title

MikroTik RouterOS Stack Buffer Overflow via TFTP URL Path

Summary

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.

Severity

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

4.3 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

CWE

CWE-121 - Stack-based Buffer Overflow

Assigner

VulnCheck mitre root

References

2 references

URL	Tags
https://mikrotik.com/supportsec/september-2026-vu…	vendor-advisorypatch
https://www.vulncheck.com/advisories/mikrotik-rou…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version	CPE status
MikroTik	RouterOS	Affected: 0 , < 7.23.4 (semver) Affected: 7.24.0 , < 7.24.2 (semver)	guessed

Date Public

2026-09-03 00:00

Credits

Kazuma Matsumoto, a security researcher at GMO Cybersecurity by IERAE, Inc.

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unknown",
          "product": "RouterOS",
          "vendor": "MikroTik",
          "versions": [
            {
              "lessThan": "7.23.4",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThan": "7.24.2",
              "status": "affected",
              "version": "7.24.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Kazuma Matsumoto, a security researcher at GMO Cybersecurity by IERAE, Inc."
        }
      ],
      "datePublic": "2026-09-03T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "MikroTik RouterOS before 7.23.4 (long-term) and 7.24.2 (stable) contains a stack-based buffer overflow vulnerability in the mtget binary\u0027s 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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "LOW",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        },
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 4.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-121",
              "description": "Stack-based Buffer Overflow",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-14T18:02:58.553Z",
        "orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
        "shortName": "VulnCheck"
      },
      "references": [
        {
          "name": "Vendor Advisory",
          "tags": [
            "vendor-advisory",
            "patch"
          ],
          "url": "https://mikrotik.com/supportsec/september-2026-vulnerability"
        },
        {
          "tags": [
            "third-party-advisory"
          ],
          "url": "https://www.vulncheck.com/advisories/mikrotik-routeros-stack-buffer-overflow-via-tftp-url-path"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "MikroTik RouterOS Stack Buffer Overflow via TFTP URL Path",
      "x_generator": {
        "engine": "vulncheck"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10",
    "assignerShortName": "VulnCheck",
    "cveId": "CVE-2026-89020",
    "datePublished": "2026-09-14T18:02:58.553Z",
    "dateReserved": "2026-09-10T16:23:54.471Z",
    "dateUpdated": "2026-09-14T18:02:58.553Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

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CVE-2026-89020 (GCVE-0-2026-89020)

Tags

Sightings

Nomenclature