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    CVE-2026-86547

    mrubyc through 4.0.0 contains a null pointer dereference vulnerability in the op_enter() handler in src/vm.c when processing untrusted bytecode. Attackers can craft malicious .mrb bytecode files with OP_ENTER instructions at the top level to crash the embedding application and cause denial of service.

    Published:Sep 9, 2026
    Last Modified:Sep 13, 2026
    EPS:Sep 9, 2026
    EPSS Score:0.00129
    CVSS Score:6.2

    Affected Products

    Vendor
    Mruby
    Product
    Mruby

    Exploits

    https://github.com/HarshRajSinghania/cve-2026-86547-mrubyc-op-enter

    Common Weakness Enumeration

    CWE-476 NULL Pointer Dereference

    Common Attack Pattern Enumeration and Classification (CAPEC)

    No CAPEC recorded yet

    Related CVEs

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    CVE-2026-1979 (CVSS 1.9) — A flaw has been found in mruby up to 3.4.0. This affects the function mrb_vm_exec of the file src/vm.c of the …
    CVE-2025-13397 (CVSS 4.8) — A security vulnerability has been detected in mrubyc up to 3.4. This impacts the function mrbc_raw_realloc of …
    CVE-2025-13120 (CVSS 1.9) — A vulnerability has been found in mruby up to 3.4.0. This vulnerability affects the function sort_cmp of the f…
    CVE-2025-12875 (CVSS 1.9) — A weakness has been identified in mruby 3.4.0. This vulnerability affects the function ary_fill_exec of the fi…
    CVE-2025-7207 (CVSS 1.9) — A vulnerability, which was classified as problematic, was found in mruby up to 3.4.0-rc2. Affected is the func…
    CVE-2021-46023 (CVSS 7.5) — An Untrusted Pointer Dereference was discovered in function mrb_vm_exec in mruby before 3.1.0-rc. The vulnerab…
    CVE-2022-1934 (CVSS 7.8) — Use After Free in GitHub repository mruby/mruby prior to 3.2.…
    CVE-2022-1427 (CVSS 7.8) — Out-of-bounds Read in mrb_obj_is_kind_of in in GitHub repository mruby/mruby prior to 3.2. # Impact: Possible …

    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
    CVE-2026-86547 — Mruby (Medium 6.9) | CVE-DB