# CVE-2026-67278: TLS server impersonation possible in Mikrotik RouterOS

> Attackers can impersonate TLS servers and bypass SSH authentication by exploiting flawed RSA signature validation in MikroTik RouterOS.

- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/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:** 5 Sep 2026
- **Updated:** 17 Sep 2026
- **Also known as:** GHSA-cq44-x9vf-fpqg

## What is CVE-2026-67278?

CVE-2026-67278 is a medium-severity vulnerability in Mikrotik Routeros, published on 5 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures across RSA-based services, including TLS/X.509 certificate validation and SSH host-key authentication. Because its trust store includes an e=3 root CA, an attacker controlling or redirecting an outbound RouterOS TLS connection can use the root’s public certificate - without its private key - to forge a trusted intermediate and issue certificates for arbitrary hostnames, enabling TLS server impersonation. The same permissive verification also undermines RSA-based SSH authentication.

This issue affects only 7.x branch was fixed in versions: 7.23.6 (Long-term) and 7.24.3 (Stable).
Releases 7.23.4 and 7.24.2 included an incomplete fix.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2026-67278?

It affects 1 product.


Products: Mikrotik Routeros.

## How do I fix CVE-2026-67278?

No fix has been published for CVE-2026-67278 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-67278 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-67278 exists.

## Other vulnerabilities in Mikrotik Routeros

- [CVE-2018-7445](https://insights.sbomify.com/CVE-2018-7445/): MikroTik RouterOS Stack-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2026-86060](https://insights.sbomify.com/CVE-2026-86060/): MikroTik RouterOS Improper Neutralization of Argument Delimiters in a Command (critical 9.2, exploited in the wild)
- [CVE-2018-14847](https://insights.sbomify.com/CVE-2018-14847/): MikroTik Router OS Directory Traversal (critical 9.1, exploited in the wild)
- [CVE-2026-67277](https://insights.sbomify.com/CVE-2026-67277/): MikroTik RouterOS Missing Authentication for Critical Function (high 8.8, exploited in the wild)
- [CVE-2026-67279](https://insights.sbomify.com/CVE-2026-67279/): Mikrotik RouterOS Improper Enforcement of Behavioral Workflow (medium 6.9, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-67278 and fix it if it is affected.

What it is: CVE-2026-67278 is a medium-severity vulnerability in Mikrotik Routeros, published on 5 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-67278 exists.

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-2026-67278/ (Markdown: https://insights.sbomify.com/CVE-2026-67278/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-67278
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-67278
- OSV: https://osv.dev/vulnerability/CVE-2026-67278

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-67278/
Summaries are generated and may contain mistakes; the official description above is the record.