CVE-2026-67278 — Mikrotik RouterOS

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. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 58 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 (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

2 tracked threats in the Threadlinqs corpus reference CVE-2026-67278, either in the campaign’s CVE list or as an indicator on the campaign record.

CISA Adds Two Actively Exploited KEVs: SharePoint Code Injection (CVE-2026-65660) and Mikrotik RouterOS Auth Bypass (CVE-2026-67279) — CRITICAL · 2026-09-26
Attackers Hijack MikroTik Routers Through Internet-Exposed SSH Without Authentication (MikroTrick) — 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