# CVE-2026-89028: MikroTik RouterOS < 7.24 Heap Corruption via SMB1 SessionSetupAndX

> Remote attackers can corrupt heap memory in MikroTik RouterOS via crafted SMB1 requests, potentially leading to code execution or service disruption.

- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Sep 2026
- **Updated:** 1 Oct 2026
- **Also known as:** GHSA-2jvh-jvq5-35jq

## What is CVE-2026-89028?

CVE-2026-89028 is a high-severity memory corruption vulnerability in MikroTik RouterOS, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-191 (Integer Underflow (Wrap or Wraparound)), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-89028?


## How do I fix CVE-2026-89028?

No fix has been published for CVE-2026-89028 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-89028 being exploited?

There is no known exploitation of CVE-2026-89028 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-89028 and fix it if it is affected.

What it is: CVE-2026-89028 is a high-severity memory corruption vulnerability in MikroTik RouterOS, published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-89028 in the wild and no public exploit code.

Affected product: MikroTik RouterOS. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-89028/ (Markdown: https://insights.sbomify.com/CVE-2026-89028/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-89028
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-89028
- OSV: https://osv.dev/vulnerability/CVE-2026-89028

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-89028/
Summaries are generated and may contain mistakes; the official description above is the record.