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    CVE-2026-39042

    An issue in MikroTIk (SIA Mikrotikls, Latvia) RouterOS 7.21.x before v.7.21.4 and 7.22.x before v.7.22.2 allows a remote attacker to cause a denial of service via the unflatten() function in libumsg.so.

    Published:Jul 13, 2026
    Last Modified:Jul 31, 2026
    EPS:Jul 13, 2026
    EPSS Score:0.00409
    CVSS Score:7.5

    Affected Products

    Vendor
    Mikrotik
    Product
    Routeros

    Exploits

    No exploit reference

    Common Weakness Enumeration

    CWE-190 Integer Overflow or Wraparound

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-92 Forced Integer Overflow

    Related CVEs

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    CVE-2026-67278 (CVSS 6.3) — MikroTik RouterOS accepts malformed RSA/PKCS#1 v1.5 signatures during X.509 validation. Because its trust stor…
    CVE-2026-67277 (CVSS 8.8) — RouterOS accepts a "related" btest connection before the corresponding primary session has completed authentic…
    CVE-2026-67276 (CVSS 9.2) — RouterOS does not compare the complete RSA public key when matching an SSH authentication request to an author…
    CVE-2026-14227 (CVSS 6.9) — An API session‑management flaw in products with the MikroTik RouterOS API enabled are vulnerable to a Insuffic…
    CVE-2026-16347 (CVSS 8.7) — MikroTik RouterOS contains a weakness in its API authentication handling that lacks effective safeguards again…
    CVE-2024-27686 (CVSS 7.5) — Mikrotik RouterOS (x86) 6.40.5 through 6.49.10 (fixed in 7) allows a remote attacker to cause a denial of serv…
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    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High