Is CVE-2026-38976 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-38976 being exploited in the wild.

How severe is CVE-2026-38976?

Informational severity, published 6 July 2026.

Is there a fix for CVE-2026-38976?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-38976 attacked?

It is attacked with local access, in a software library.

Am I affected by CVE-2026-38976?

Check whether you run Mrubyc at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-38976: mrubyc NULL pointer dereference in op_super

CVE-2026-38976 · Severity: info · Published 2026-07-06

mruby/c is a lightweight implementation of the Ruby programming language designed for microcontrollers and embedded systems with limited memory. A vulnerability was found where the software crashes when it encounters a 'super' command used in an improper context, such as at the top level of a script. This allows a specially crafted program to shut down the interpreter, potentially causing a denial-of-service for the device or application using it.

Technologies: Mrubyc. Vendors: Mrubyc.

Quick answers

Is CVE-2026-38976 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-38976 being exploited in the wild.
How severe is CVE-2026-38976?: Informational severity, published 6 July 2026.
Which products and versions are affected?: Mrubyc through 3.4.1.
Is there a fix for CVE-2026-38976?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-38976 attacked?: It is attacked with local access, in a software library.
Am I affected by CVE-2026-38976?: Check whether you run Mrubyc at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A NULL pointer dereference exists in src/vm.c within the op_super() function (OP_SUPER opcode). The vulnerability is caused by a missing runtime guard when 'super' is called at the top-level or outside of a method context, where vm->callinfo_tail is NULL. An attacker who can provide or execute arbitrary mruby bytecode (.mrb files) can trigger this dereference, leading to a process crash (Denial of Service). This issue is similar to CVE-2022-1201 in the main mruby implementation. A fix has been identified that adds a check for NULL callinfo and raises a NoMethodError instead of crashing.

Affected products

mrubyc mrubyc through 3.4.1

Timeline

2026-03-19: disclosed: Issue reported on GitHub
2026-07-06: advisory: CVE published to NVD

References

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