CVE Intelligence
CISA KEV High Authentication exploit reference

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

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. This issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)

Published Sep 5, 2026 · Updated Oct 13, 2026 · Sources: CISA Known Exploited Vulnerabilities, NIST National Vulnerability Database, GitHub Security Advisories, CVE Program (cve.org) e CISA ADP · CNA: CERT-PL

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

CISA KEV · Sep 10, 2026
How the score was calculated
  • Confirmed exploitation (CISA KEV)+35
  • EPSS 1.6% (30-day exploitation probability)+11
  • Technical severity (high)+6
  • Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Confirmed
CISA KEV, listed Sep 10, 2026
EPSS FIRST
1.56%
ahead of 75% of scored CVEs · Oct 14, 2026
Affects
Mikrotik
Routeros
CVSS base
8.2
High · 4 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
Active
none · proof-of-concept · active
Automatable
Yes
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

  • Documented mitigation — cert.pl (NIST National Vulnerability Database)

CISA required action CISA

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

US federal deadline: Sep 13, 2026 — passed 32 day(s) ago

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Mikrotik Routeros).
  2. Treat as emergency remediation: the CVE is in CISA KEV (confirmed exploitation).
  3. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  4. Apply the documented mitigations until a definitive fix is available.
  5. Search available logs for exploit probes matching the vulnerability class (authentication), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Mikrotik Routeros ≥ 6.0 and < 6.49.21≥ 7.0 and < 7.23.4≥ 7.24 and < 7.24.2 Vulnerable NIST National Vulnerability Database
Mikrotik Routeros ≥ 7.24 and < 7.24.2≥ 7.0.0 and < 7.23.4≥ 6.0.0 and < 6.49.21 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
8.8 CVSS 4.0 High — — cvd@cert.pl via NIST National Vulnerability Database
8.8 CVSS 4.0 High — — CERT-PL via CVE Program (cve.org) e CISA ADP
8.2 CVSS 3.1 High 3.9 4.2 nvd@nist.gov via NIST National Vulnerability Database
8.2 CVSS 3.1 High — — GitHub, Inc. via GitHub Security Advisories
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-306 · Missing Authentication for Critical Function

Other CVEs with this weakness →

CISA KEV details CISA

CISA lists a CVE once it has evidence of exploitation against real targets.

Listed
Sep 10, 2026
Federal deadline
Sep 13, 2026
passed 32 day(s) ago
Ransomware use
Unknown

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a reference date.

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 1.56%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Review authentication logs: logins without MFA, anomalous sessions and recently created accounts.
  • Hunt retroactively in logs from before Sep 10, 2026 (KEV listing): exploitation may have started earlier.
web/proxy/WAF logsnetwork IDS/IPSauthentication logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · mikrotik/routeros
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • Fix documented
    Oct 13, 2026 · NIST National Vulnerability Database
  • Affected products added · mikrotik/routeros
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVSS changed · 8.2
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Analyzed
    Oct 13, 2026 · NIST National Vulnerability Database
  • Added to CISA KEV (detected)
    Oct 13, 2026 · CISA Known Exploited Vulnerabilities
  • Record created in this database
    Oct 13, 2026 · CISA Known Exploited Vulnerabilities
  • Added to CISA KEV catalog
    Sep 9, 2026 · CISA
  • CVE published
    Sep 5, 2026 · CERT-PL

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 13, 2026 – Oct 13, 2026
  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

13 on the record

Elsewhere on this site

Mikrotik
every CVE for this vendor
2026-09
what else CISA listed that month
Authentication
same class
CWE-306
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-103903 MikroTik RouterOS WinBox split-principal authentication bypass allows privilege escalation 3d
  • CVE-2026-84411 MikroTik RouterOS Integer Underflow 12d
  • CVE-2026-86060 MikroTik RouterOS Improper Neutralization of Argument Delimiters in a Command Vulnerability KEV Sep 5, 2026
  • CVE-2026-67279 Mikrotik RouterOS Improper Enforcement of Behavioral Workflow Vulnerability KEV Sep 5, 2026
  • CVE-2025-42611 Improper certificate validation in multiple RouterOS services May 5, 2026
  • CVE-2026-7668 MikroTik RouterOS SCEP Endpoint scep.p ASN1_STRING_data out-of-bounds May 2, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-67277 is "MikroTik RouterOS Missing Authentication for Critical Function Vulnerability", rated High. It affects Routeros (Mikrotik); versions are in the scope table. It is in CISA KEV: there is evidence of real-world exploitation. CVSS 8.2 describes technical severity. EPSS 1.56% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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