Quick answers
- Is CVE-2026-123839 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-123839 being exploited in the wild.
- How severe is CVE-2026-123839?
- Medium severity, with a CVSS score of 4.7, published 6 November 2026.
- Which products and versions are affected?
- Jetbrains IntelliJ IDEA before 2026.3.
- Is there a fix for CVE-2026-123839?
- Yes: fixed in IntelliJ IDEA 2026.3. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-123839 attacked?
- It is attacked over the network, in a web application.
- Am I affected by CVE-2026-123839?
- Check whether you run Jetbrains IntelliJ IDEA 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: IntelliJ IDEA 2026.3
Technical details
The vulnerability exists in IntelliJ IDEA's Remote Development port forwarding model, which failed to validate or confirm URLs before opening them. This allows an attacker with network access to the forwarding mechanism to trigger arbitrary URL opening, bypassing the expected user confirmation. The issue affects versions before 2026.3.
Affected products
- JetBrains IntelliJ IDEA before 2026.3
Timeline
- 2026-11-06: disclosed