# CVE-2026-56719: MikroTik RouterOS < 7.24 Out-of-Bounds Read via SMB1 SessionSetupAndX

> Unauthenticated attackers can read sensitive memory contents via a crafted SMB1 packet in MikroTik RouterOS, requiring an upgrade to mitigate.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:L/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-w9p3-2qvw-6779

## What is CVE-2026-56719?

CVE-2026-56719 is a medium-severity 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 an out-of-bounds read vulnerability in the userspace SMB daemon that allows unauthenticated attackers to read beyond the end of the request buffer by supplying a crafted uniPwdLen field value in a minimal SMB1 SessionSetupAndX frame. The out-of-bounds read occurs in the SessionSetupAndX handler before any credential validation, potentially exposing sensitive memory contents.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-56719?


## How do I fix CVE-2026-56719?

No fix has been published for CVE-2026-56719 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-56719 being exploited?

There is no known exploitation of CVE-2026-56719 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-56719 and fix it if it is affected.

What it is: CVE-2026-56719 is a medium-severity 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-2026-56719 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-2026-56719/ (Markdown: https://insights.sbomify.com/CVE-2026-56719/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-56719
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-56719
- OSV: https://osv.dev/vulnerability/CVE-2026-56719

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-56719/
Summaries are generated and may contain mistakes; the official description above is the record.