Is CVE-2026-123831 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-123831 being exploited in the wild.

How severe is CVE-2026-123831?

Critical severity, with a CVSS score of 9.6, published 6 November 2026.

Which products and versions are affected?

Jetbrains CLion before 2026.2 and 2026.1.4.

Is there a fix for CVE-2026-123831?

Yes: fixed in CLion 2026.2, 2026.1.4. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-123831 attacked?

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

Am I affected by CVE-2026-123831?

Check whether you run Jetbrains CLion 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-2026-123831: JetBrains CLion code execution in Safe Mode via Meson settings

CVE-2026-123831 · Severity: critical · CVSS 9.6 · Published 2026-11-06

JetBrains CLion is an integrated development environment (IDE) for C and C++ development. A critical vulnerability allowed attackers to execute arbitrary code even when CLion was running in Safe Mode, by manipulating Meson project configuration files. This could allow an attacker to gain full control of a developer's machine through a malicious project.

Technologies: Jetbrains CLion. Vendors: Jetbrains.

Quick answers

Is CVE-2026-123831 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-123831 being exploited in the wild.
How severe is CVE-2026-123831?: Critical severity, with a CVSS score of 9.6, published 6 November 2026.
Which products and versions are affected?: Jetbrains CLion before 2026.2 and 2026.1.4.
Is there a fix for CVE-2026-123831?: Yes: fixed in CLion 2026.2, 2026.1.4. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-123831 attacked?: It is attacked with local access, in a software library.
Am I affected by CVE-2026-123831?: Check whether you run Jetbrains CLion 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.

How to fix

Fixed in: CLion 2026.2, 2026.1.4

Technical details

The vulnerability is a code execution flaw in CLion's Safe Mode that is bypassed via Meson project settings, allowing arbitrary command execution when a user opens a malicious project. The vulnerability affects CLion versions prior to 2026.2 and 2026.1.4. No special authentication or user interaction beyond opening a project is required.

Affected products

JetBrains CLion before 2026.2 and 2026.1.4

Timeline

2026-11-06: disclosed

References

https://www.jetbrains.com/privacy-security/issues-fixed/

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