Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| mrubyc | mrubyc | 2.0 – ≤ 4.0.0 | — |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
GitHub 1 repository
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HarshRajSinghania/cve-2026-86547-mrubyc-op-enter ★ 0 · Sep 12, 2026
Standalone proof of concept for CVE-2026-86547, a NULL pointer dereference in mrubyc op_enter() through 4.0.0.
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
References
- https://github.com/mrubyc/mrubyc/blob/release4.0.0/src/vm.c#L1537 technical-description
- https://github.com/mrubyc/mrubyc/blob/4261cf5e5ae5579e3110dab98a04b91c7d919429/src/vm.c#L1534 technical-description
- VulnCheck Advisory: mrubyc through 4.0.0 NULL Pointer Dereference via OP_ENTER third-party-advisory