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Full vulnerability report · 2026
CVE-2026-67278High confidence

TLS server impersonation possible in Mikrotik RouterOS

Mikrotik · RouterOS

6.3MediumCVSS 4.0
Recommended action
Within 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Mitigation available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:High, raised one band.upgradedsince 17 Sep 2026

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.25% for the current model date.

Compensating controls

  • Apply the linked authoritative mitigation while planning the permanent fix.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Mikrotik RouterOS and falls inside the recorded affected range.
  2. Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-72026

No EUVD known-exploited evidence

MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures across RSA-based services, including TLS/X.509 certificate validation and SSH host-key authentication. 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. The same permissive verification also undermines RSA-based SSH authentication. This issue affects only 7.x branch was fixed in versions: 7.23.6 (Long-term) and 7.24.3 (Stable). Releases 7.23.4 and 7.24.2 included an incomplete fix.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
6.3 · CVSS 4.0
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Mitigation available
01

What, why and how

MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures across RSA-based services, including TLS/X.509 certificate validation and SSH host-key authentication. 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. The same permissive verification also undermines RSA-based SSH authentication. This issue affects only 7.x branch was fixed in versions: 7.23.6 (Long-term) and 7.24.3 (Stable). Releases 7.23.4 and 7.24.2 included an incomplete fix.

What

MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures across RSA-based services, including TLS/X.509 certificate validation and SSH host-key authentication. 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. The same permissive verification also undermines RSA-based SSH authentication. This issue affects only 7.x branch was fixed in versions: 7.23.6 (Long-term) and 7.24.3 (Stable). Releases 7.23.4 and 7.24.2 included an incomplete fix.

Why

The product does not verify, or incorrectly verifies, the cryptographic signature for data.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures across RSA-based services, including TLS/X.509 certificate validation and SSH host-key authentication. 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. The same permissive verification also undermines RSA-based SSH authentication. This issue affects only 7.x branch was fixed in versions: 7.23.6 (Long-term) and 7.24.3 (Stable). Releases 7.23.4 and 7.24.2 included an incomplete fix.

Why

The product does not verify, or incorrectly verifies, the cryptographic signature for data.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Improper Verification of Cryptographic Signature → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-347 ↗

CWE-347: Improper Verification of Cryptographic Signature. The product does not verify, or incorrectly verifies, the cryptographic signature for data.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
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

Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATPresentAttack requirements: A particular deployment or execution condition must be present.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCLowVulnerable-system confidentiality: A successful attack can cause a limited loss.VILowVulnerable-system integrity: A successful attack can cause a limited loss.VANoneVulnerable-system availability: No direct loss is represented by this metric.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-347Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-72026Official EUVD mapping

MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures across RSA-based services, including TLS/X.509 certificate validation and SSH host-key authentication. 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. The same permissive verification also undermines RSA-based SSH authentication. This issue affects only 7.x branch was fixed in versions: 7.23.6 (Long-term) and 7.24.3 (Stable). Releases 7.23.4 and 7.24.2 included an incomplete fix.

Official EUVD record ↗
BSI · German · WID-SEC-2026-3193MikroTik RouterOS: Mehrere Schwachstellen

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in MikroTik RouterOS ausnutzen, um Sicherheitsvorkehrungen zu umgehen, um Informationen offenzulegen, um einen Denial of Service Zustand herbeizuführen und um die Kontrolle über betroffene Geräte zu übernehmen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260909Security Bulletin 9 Sep 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 9 Sep 2026, published on 9 September 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-035744MikroTikのrouterosにおけるデジタル署名の検証に関する脆弱性

MikroTik RouterOSは、TLS/X.509証明書の検証やSSHホストキー認証を含むRSAベースのサービス全体で、不正な形式のRSA/PKCS#1 v1.5署名を受け入れてしまいます。信頼ストアにe=3のルートCAが含まれているため、攻撃者がRouterOSのアウトバウンドTLS接続を制御またはリダイレクトできる場合、プライベートキーなしでルートの公開証明書を使用して信頼された中間証明書を偽造し、任意のホスト名の証明書を発行することが可能になるため、TLSサーバのなりすましを行うことができます。同様に、寛容すぎる検証によりRSAベースのSSH認証も脆弱になります。本問題は7.x系のみが影響を受け、バージョン7.23.6（長期サポート）および7.24.3（安定版）で修正されました。なお、リリース7.23.4および7.24.2では修正が不完全でした。

Official advisory ↗
CERT Polska · Polish · mikrotik-routeros-cveCERT Polska w social mediach

Podczas badań własnych Sławomir Rozbicki z zespołu CERT Polska odkrył podatności w oprogramowaniu MikroTik RouterOS i wraz z pozostałymi członkami zespołu uczestniczył w koordynacji ich ujawnienia. Szczegóły dotyczące tego, w jaki sposób odkryto te podatności, wraz z innymi powiązanymi informacjami, są dostępne w naszym osobnym artykule . Podatność CVE-2026-67276 : RouterOS nie porównuje kompletnego klucza publicznego RSA podczas dopasowywania żądania uwierzytelnienia SSH do klucza autoryzowanego użytkownika, sprawdzając typ klucza i moduł, ale pomijając wykładnik. Ponieważ weryfikacja podpisu wykorzystuje klucz dostarczony przez klienta, atakujący znający autoryzowany moduł RSA może dostarczyć klucz z wykładnikiem równym jeden, sfałszować prawidłowy podpis i otworzyć kanał poleceń SSH jako docelowy użytkownik bez klucza prywatnego. Podatność CVE-2026-67277 : RouterOS akceptuje połączenie btest typu "related" przed zakończeniem uwierzytelniania odpowiadającej mu głównej sesji. Nieuwierzytelniony klient może wykorzystać ten stan do uruchomienia testu IPv4 UDP. Przy ustawieniu "random-data=false" nadawca transmituje niezainicjowany fragment końcowy z bufora pakietów jądra. Osobny, niesprawdzany i odwrócony przedział rozmiaru pakietu powoduje błąd typu integer underflow, co umożliwiało wyciek pamięci jądra albo zdalny atak DoS prowadzący do restartu systemu. Podatność CVE-2026-67279 : RouterOS SSH przechodzi do protokołu połączenia po zażądanej przez klienta renegocjacji kluczy, mimo że nie podjęto próby uwierzytelnienia użytkownika, co umożliwia nieuwierzytelnionemu klientowi otwarcie kanału sesji i wysłanie żądania exec. W podatnych wersjach serwer wykonuje polecenie, umożliwiając nieuwierzytelnione utworzenie, nadpisanie i odtworzenie plików w przestrzeni nazw plików zarządzanej przez RouterOS, w tym plików pomocniczych zawierających dane konfiguracyjne i diagnostyczne. Podatność CVE-2026-67281 : RouterOS WebFig zawiera podatność umożliwiającą nieuwierzytelniony odczyt plików poprzez ścieżkę /jsproxy , w której nowo utworzona sesja zachowuje nieaktualny, niezainicjalizowany wskaźnik do danych określających uprawnienia, wykorzystywany podczas autoryzacji dostępu do plików. Nieuwierzytelniony atakujący może odpowiednio przygotować stan alokatora pamięci, aby mechanizm udostępniania plików wykorzystał ten wskaźnik z wystarczającymi uprawnieniami, a następnie użyć komponentów wskazujących na katalog nadrzędny w zaszyfrowanym URI w celu opuszczenia przestrzeni plików WebFig i ujawnienia plików należących do użytkownika root, w tym plików konfiguracyjnych zawierających dane uwierzytelniające. Podatność CVE-2026-86060 : RouterOS zawiera błąd w obsłudze argumentów w ścieżce logowania SSH, dotyczący nazw użytkowników zaczynających się od zabronionego znaku. Pozwala to na zmianę zaufanej maski polityk RouterOS, co prowadzi do eskalacji uprawnień. Wykorzystanie tej luki wymaga nieautoryzowanej sesji SSH. Problemy te zostały naprawione w wersjach: 6.49.21 (Long-term), 7.23.4 (Long-term) i 7.24.2 (Stable). Podatność CVE-2026-67278 : MikroTik RouterOS akceptuje nieprawidłowe podpisy RSA/PKCS#1 v1.5 w usługach opartych na RSA, w tym podczas walidacji certyfikatów TLS/X.509 oraz uwierzytelniania klucza hosta SSH. Ponieważ magazyn zaufanych certyfikatów (trust store) zawiera główny certyfikat CA z wykładnikiem e=3, atakujący kontrolujący lub przekierowujący wychodzące połączenie TLS z RouterOS może wykorzystać publiczny certyfikat głównego CA – bez posiadania jego klucza prywatnego – do sfałszowania zaufanego certyfikatu pośredniego i wystawienia certyfikatów dla dowolnych nazw hostów, co umożliwia podszycie się pod serwer TLS. Ten sam problem wpływa również na uwierzytelnianie SSH oparte na RSA. Problem dotyczy wyłącznie gałęzi 7.x i został naprawiony w wersjach: 7.23.6 (Long-term) oraz 7.24.3 (Stable). Wersje 7.23.4 oraz 7.24.2 zawierały niepełną poprawkę. Dziękujemy Robertowi Żegleniowi za zgłoszenie tego problemu. Więcej o procesie zgłaszania podatności można przeczytać na stronie https://cert.pl/cvd/ . CERT Polska to zespół działający w strukturach NASK - Państwowego Instytutu Badawczego, powołany w 1996 roku do reagowania na incydenty bezpieczeństwa komputerowego. Realizuje zadania CSIRT NASK, jednego z trzech takich zespołów działających na poziomie krajowym w ramach krajowego systemu cyberbezpieczeństwa. CERT Polska w social mediach Facebook X LinkedIn GitHub Kontakt ul. Kolska 12, 01-045 Warszawa ePUAP: /NASK-Instytut/SkrytkaESP e-Doręczenia: AE:PL-60057-61611-BCEGR-11 e-mail: [email protected] Zgłaszanie incydentów: incydent.cert.pl [email protected] © 2026 NASK Polityka prywatności Deklaracja dostępności CSIRT GOV CSIRT MON

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Mitigation available
Affected
RouterOS: 7.24 < 7.24.3, 7.0.0 < 7.23.6
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
Apply the mitigation in the linked authoritative guidance while planning the vendor's permanent fix.
Workaround
A mitigation or workaround reference is available from the source linked below; validate it against the affected product and version.
04

Evidence and provenance

Published 5 Sept 2026 · Last source change 17 Sept 2026, 14:20 UTC · CWE-347 · Improper Verification of Cryptographic Signature

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-09-06
European sourceENISA EUVD · EUVD-2026-72026
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Vendor guidanceAuthoritative vendor guidance changed: added mitigation: cert.pl/vulnerabilities-in-mikrotik-routeros-actively-exploited; added remediation: cert.pl/vulnerabilities-in-mikrotik-routeros-actively-exploited; 1 further additions.
    Before
    no authoritative guidance recorded
    After
    mitigation: cert.pl/vulnerabilities-in-mikrotik-routeros-actively-exploited · remediation: cert.pl/vulnerabilities-in-mikrotik-routeros-actively-exploited · vendor advisory: mikrotik.com/september-2026-vulnerability
    cvd@cert.pl ↗
  2. Remediation statusRemediation status changed from Awaiting fix to Mitigation available.
    Before
    Awaiting fix
    After
    Mitigation available
    cvd@cert.pl ↗
  3. Public exploit evidencePublic exploit evidence changed from Public exploit reference to Public exploit reference.
    Before
    Public exploit reference
    After
    Public exploit reference
    cvd@cert.pl ↗
  4. Affected versionsThe structured affected or fixed version information changed.
    Before
    RouterOS: 7.24 < 7.24.2, 7.0.0 < 7.23.4 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    RouterOS: 7.24 < 7.24.3, 7.0.0 < 7.23.6 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  5. BlackTree coverageBlackTree article coverage changed from no BlackTree article to 1 BlackTree article.
    Before
    no BlackTree article
    After
    1 BlackTree article
    BlackTree editorial ↗
  6. Affected versionsThe structured affected or fixed version information changed.
    Before
    7.24 < 7.24.2; 7.0.0 < 7.23.4 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    RouterOS: 7.24 < 7.24.2, 7.0.0 < 7.23.4 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  7. Public exploit evidencePublic exploit evidence changed from No public exploit to Public exploit reference.
    Before
    No public exploit
    After
    Public exploit reference
    CVE.org ↗
  8. Affected versionsThe structured affected or fixed version information changed.
    Before
    7.24 < 7.24.2; 7.0.0 < 7.23.4; 6.0.0 < 6.49.21 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    7.24 < 7.24.2; 7.0.0 < 7.23.4 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  9. ENISA EUVD mappingEUVD-2026-72026 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-72026"}
    ENISA EUVD ↗
  10. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Mitigation reference recorded
ENISA EUVD · EUVD-2026-72026↗CISA Vulnrichment SSVC evidence↗Mitigation reference↗Vendor advisory↗CVE authority or vendor reference↗Public exploit reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-67278 · cve.blacktree.nl