# CVE-2026-67278 — Mikrotik RouterOS > As of 2026-09-05, CVE-2026-67278 is a Medium-severity (band derived from the CVSS v4.0 score, not stated by the CNA) vulnerability in Mikrotik RouterOS, CVSS v4.0 6.3, EPSS 0.1% (6.2th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-67278, most recently “Attackers Hijack MikroTik Routers Through Internet-Exposed SSH Without Authentication (MikroTrick)”. **Last updated:** 2026-09-05 ## What is CVE-2026-67278? MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures during X.509 validation. 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. This issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable) The record classifies CVE-2026-67278 under weakness class [CWE-347](https://cwe.mitre.org/data/definitions/347.html). 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 13 days ago. ## Severity and exploitation probability - **CVSS v4.0 base score:** 6.3 — Medium (derived from score) (`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`) - **EPSS (FIRST):** 0.1% probability of exploitation in the next 30 days, higher than 6.2% of all scored CVEs - **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog - **Threadlinqs priority:** 5.4/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability - **Published:** 2026-09-05 ## Is CVE-2026-67278 being exploited? Weaponised exploit code for CVE-2026-67278 is publicly available. 1 public proof-of-concept repository is tracked for this identifier. It currently carries a trending score of 39 in the Threadlinqs vulnerability feed. - [trickest/cve](https://github.com/trickest/cve/blob/main/2026/CVE-2026-67278.md) (trickest) ## Affected products and versions - **Mikrotik**: RouterOS ## How to fix CVE-2026-67278 No vendor patch reference has been recorded for CVE-2026-67278 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise. ## Threat activity tracking CVE-2026-67278 1 tracked threat in the Threadlinqs corpus references CVE-2026-67278, either in the campaign’s CVE list or as an indicator on the campaign record. - [Attackers Hijack MikroTik Routers Through Internet-Exposed SSH Without Authentication (MikroTrick)](https://intel.threadlinqs.com/threat/TL-2026-2345) — CRITICAL · 2026-09-06 ## Sources Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories, public proof-of-concept repositories. Last verified by Threadlinqs on 2026-09-06. This product uses the NVD API but is not endorsed or certified by the NVD. **Vendor advisory and patch** - [mikrotik.com — vendor advisory](https://mikrotik.com/supportsec/september-2026-vulnerability/) - [forum.mikrotik.com — release notes](https://forum.mikrotik.com/t/6-49-21-long-term-is-released/272802) - [forum.mikrotik.com — release notes (272801)](https://forum.mikrotik.com/t/7-23-4-long-term-is-released/272801) - [forum.mikrotik.com — release notes (272800)](https://forum.mikrotik.com/t/7-24-2-stable-is-released/272800) **Exploit and proof of concept** - [npratley.net — exploit](https://npratley.net/reversing-mikrotiks-silent-patch-the-routeros-7-23-4-fix-they-wouldnt-explain/) **Technical analysis** - [cert.pl — technical description](https://cert.pl/en/posts/2026/09/vulnerabilities-in-mikrotik-routeros-actively-exploited/) **Third-party advisory** - [cert.pl — third party advisory](https://cert.pl/en/posts/2026/09/mikrotik-routeros-cve) Canonical: https://intel.threadlinqs.com/cve/CVE-2026-67278 Full detection coverage and IOCs for threats exploiting CVE-2026-67278 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp