mrubyc through 4.0.0 contains a null pointer dereference vulnerability in the op_enter() handler in src/vm.c when processing untrusted bytecode. (CVE-2026-86547)
mrubyc versions through 4.0.0 contain a null pointer dereference vulnerability in the op_enter() handler located in src/vm.c. This flaw occurs when processing untrusted .mrb bytecode files containing OP_ENTER instructions at the top level. Exploitation results in a crash of the embedding application, causing denial of service.
AI Analysis
Technical Summary
The vulnerability identified as CVE-2026-86547 affects mrubyc up to version 4.0.0. It is a null pointer dereference in the op_enter() handler within src/vm.c, triggered by maliciously crafted .mrb bytecode files with OP_ENTER instructions at the top level. This causes the embedding application to crash, leading to denial of service. The CVSS 3.1 score is 6.2 (medium severity), with attack vector local, low complexity, no privileges required, no user interaction, and impact limited to availability.
Potential Impact
Successful exploitation causes a denial of service by crashing the embedding application due to a null pointer dereference. There is no confidentiality or integrity impact reported. The attack requires local access to supply malicious bytecode.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, avoid processing untrusted .mrb bytecode files or implement input validation to prevent OP_ENTER instructions at the top level.
mrubyc through 4.0.0 contains a null pointer dereference vulnerability in the op_enter() handler in src/vm.c when processing untrusted bytecode. (CVE-2026-86547)
Description
mrubyc versions through 4.0.0 contain a null pointer dereference vulnerability in the op_enter() handler located in src/vm.c. This flaw occurs when processing untrusted .mrb bytecode files containing OP_ENTER instructions at the top level. Exploitation results in a crash of the embedding application, causing denial of service.
CVSS v3.1
Score 6.2medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability identified as CVE-2026-86547 affects mrubyc up to version 4.0.0. It is a null pointer dereference in the op_enter() handler within src/vm.c, triggered by maliciously crafted .mrb bytecode files with OP_ENTER instructions at the top level. This causes the embedding application to crash, leading to denial of service. The CVSS 3.1 score is 6.2 (medium severity), with attack vector local, low complexity, no privileges required, no user interaction, and impact limited to availability.
Potential Impact
Successful exploitation causes a denial of service by crashing the embedding application due to a null pointer dereference. There is no confidentiality or integrity impact reported. The attack requires local access to supply malicious bytecode.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, avoid processing untrusted .mrb bytecode files or implement input validation to prevent OP_ENTER instructions at the top level.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-42q4-rvcw-q7wc
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-86547"]
- Ecosystems
- []
- Database Specific Severity
- MODERATE
- Cvss Version
- 3.1
Threat ID: 6aa15f17acd9273b496159e1
Added to database: 09/09/2026, 13:28:55 UTC
Last enriched: 09/09/2026, 13:33:19 UTC
Last updated: 09/09/2026, 21:52:09 UTC
Views: 3
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