Quick answers
- Is CVE-2026-123851 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-123851 being exploited in the wild.
- How severe is CVE-2026-123851?
- Medium severity, with a CVSS score of 5.4, published 6 November 2026.
- Which products and versions are affected?
- Jetbrains Junie GitHub Action before 1.6.4.
- Is there a fix for CVE-2026-123851?
- Yes: fixed in 1.6.4. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-123851 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-123851?
- Check whether you run Jetbrains Junie GitHub Action 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: 1.6.4
Technical details
The vulnerability is a prompt injection bypass in JetBrains Junie GitHub Action before version 1.6.4, where HTML-encoded characters are not properly sanitized before being passed to language models or similar processing systems. An attacker with the ability to create pull requests or supply input to the action can craft specially-encoded payloads to circumvent input validation, potentially leading to unintended model behavior or data exposure.
Affected products
- JetBrains Junie GitHub Action before 1.6.4
Timeline
- 2026-11-06: disclosed