CVE-2026-67278

Analyzed Analyzed - Analysis Complete

RSA Signature Forgery in MikroTik RouterOS

Publication date: 2026-09-05

Last updated on: 2026-09-25

Assigner: CERT.PL

Description

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 affects only 7.x branch was fixed in versions: 7.23.4 (Long-term) and 7.24.2 (Stable)

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-09-05

Last Modified

2026-09-25

Generated

2026-09-26

AI Q&A

2026-09-05

EPSS Evaluated

2026-09-24

NVD

CVE-2026-67278

EUVD

EUVD-2026-72026

Affected Vendors & Products

Vendor	Product	Version / Range
mikrotik	routeros	From 7.0 (inc) to 7.23.6 (exc)
mikrotik	routeros	From 7.24 (inc) to 7.24.3 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-347	The product does not verify, or incorrectly verifies, the cryptographic signature for data.

Attack-Flow Graph

Executive Summary

MikroTik RouterOS has a flaw where it accepts malformed RSA/PKCS#1 v1.5 signatures during X.509 certificate validation. Because the trust store includes a root CA with a public exponent of 3, an attacker can forge trusted intermediate certificates and issue certificates for any hostname without needing the root CA's private key. This allows TLS server impersonation for outbound RouterOS TLS connections.

Detection Guidance

This vulnerability is specific to MikroTik RouterOS versions prior to 6.49.21, 7.23.4, and 7.24.2. To detect it, check your RouterOS version using the command 'system package print' and verify if it is below the fixed versions. Additionally, inspect TLS certificates used by RouterOS for any anomalies in signature validation.

Impact Analysis

This vulnerability enables attackers to impersonate trusted servers during TLS connections initiated by MikroTik RouterOS devices. If exploited, it could allow interception of sensitive data, such as login credentials or other confidential information, transmitted through these connections.

Compliance Impact

This vulnerability could lead to unauthorized access to personal or sensitive data, violating GDPR's data protection requirements and HIPAA's security rules for protected health information. Organizations using affected MikroTik RouterOS versions may fail to meet compliance standards due to insufficient protection against TLS impersonation attacks.

Mitigation Strategies

Upgrade MikroTik RouterOS to version 6.49.21, 7.23.4, or 7.24.2 or later to address the vulnerability.

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