CVE-2026-67277: MikroTik RouterOS Missing Authentication for Critical Function Vulnerability

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HIGH 8.2EXPLOITEDREMOTEUPGRADE

CVE-2026-67277 is a high-severity flaw (CVSS 8.2) affecting routeros, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

RouterOS accepts a "related" btest connection before the corresponding primary session has completed authentication. An unauthenticated client can use this state to start an IPv4 UDP test. With "random-data=false", the sender transmits an uninitialized tail from a kernel packet buffer. A separate unchecked, inverted packet-size interval causes unsigned integer underflow, anomalously large fragmented output, and can restart the RouterOS kernel.

Why this priority

High severity
Exploited in the wild (CISA KEV)
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.2 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.6% (top 25%)
CISA exploited list	Yes, fix due 2026-09-13
Weakness	CWE-306
Published	2026-09-05
Last modified	2026-09-11

Publisher (CNA): CERT.PL · Vendor: mikrotik

Am I affected?

Timeline

2026-09-05 20:17 UTCPublished CVE record published
2026-09-10Exploited Added to the CISA Known Exploited Vulnerabilities list
2026-09-11 12:52 UTCUpdated Record last modified
2026-09-13Deadline CISA due date for US federal agencies to patch

mikrotik routeros UPGRADE

Affected: >= 6.0 and < 6.49.21 · >= 7.0 and < 7.23.4 · >= 7.24 and < 7.24.2

Fixed in: 6.49.21, 7.23.4, 7.24.2

Safe to downgrade to: a release before 6.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

Fedora 46 · retext · FIXED · 8.1.0-1.fc46 · FEDORA-2026-0602a84203 · source

sudo dnf upgrade --advisory=FEDORA-2026-0602a84203

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: forum.mikrotik.com/t/7-24-2-stable-is-released/272800

Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Related CVEs

CVE-2026-67279 MEDIUM 6.5 EXPLOITED UPGRADE Mikrotik RouterOS Improper Enforcement of Behavioral Workflow Vulnerability
CVE-2026-86060 CRITICAL 9.8 EXPLOITED UPGRADE MikroTik RouterOS Improper Neutralization of Argument Delimiters in a Command Vulnerability

References

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