CVE-2026-67278Network attack vector

TLS server impersonation via malformed RSA signatures

Published Sep 5, 2026 · Updated Sep 8, 2026

Improper signature verification in MikroTik RouterOS 7.0.0 through 7.23.3 and 7.24 through 7.24.1 allows remote attackers to impersonate TLS servers. The X.509 verifier accepts malformed PKCS#1 v1.5 signatures, letting attackers use the public certificate of an e=3 trusted root to forge an intermediate certificate for arbitrary hostnames. Exploitation requires control or redirection of an outbound TLS connection; the forged chain permits trusted impersonation without the root private key and enables intercepted traffic to be read or altered.

CVSS severity6.3
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper signature verification in MikroTik RouterOS 7.0.0 through 7.23.3 and 7.24 through 7.24.1 allows remote attackers to impersonate TLS servers. The X.509 verifier accepts malformed PKCS#1 v1.5 signatures, letting attackers use the public certificate of an e=3 trusted root to forge an intermediate certificate for arbitrary hostnames. Exploitation requires control or redirection of an outbound TLS connection; the forged chain permits trusted impersonation without the root private key and enables intercepted traffic to be read or altered.

The record

CVE
CVE-2026-67278
Published
Sep 5, 2026
Updated
Sep 8, 2026
Vendor
MikroTik
Product
RouterOS
Classifications
CWE-347, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 5, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=7.0.0 <7.23.4
  2. Affected versionversion=7.24 <7.24.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

MikroTik · RouterOSversion=7.0.0 <7.23.4; version=7.24 <7.24.2

Published CVSS scores

6.3GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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