CVE-2026-86547
MediumCVSS 6.2Exploitation Probability (EPSS)
Low risk3th percentile - higher than 3% of all known CVEs
Summary
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 files with OP_ENTER instructions at the top level to crash the embedding application and cause denial of service.
Risk Assessment
The risk includes application crashes, which could lead to service disruptions.
Recommendation
Update mrubyc to a version newer than 4.0.0 if a patch is available. Additionally, avoid processing untrusted bytecode and validate inputs.
Other vulnerabilities in mrubyc
See all- CVE-2026-38976High
In mrubyc up to version 3.4.1, a NULL pointer dereference was found in the op_super() function in src/vm.c due to a missing runtime guard for top-level super calls.
- CVE-2026-38973Medium
An out-of-bounds read was found in mrubyc up to release 3.4.1 during builtin missing-method lookup in mrbc_find_method().
- CVE-2025-13397Low
mrubyc up to 3.4 has a vulnerability in the mrbc_raw_realloc function in src/alloc.c. Manipulation of the ptr argument leads to a null pointer dereference. The attack requires local access, and the patch is identified by commit 009111904807b8567262036bf45297c3da8f1c87.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS