Quick answers
- Is CVE-2026-100277 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-100277 being exploited in the wild.
- How severe is CVE-2026-100277?
- High severity, with a CVSS score of 8.9, published 30 September 2026.
- Which products and versions are affected?
- Jetbrains YouTrack before 2026.2.19197.
- Is there a fix for CVE-2026-100277?
- 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-2026-100277 attacked?
- It is attacked over the network, in a web application.
- Am I affected by CVE-2026-100277?
- Check whether you run Jetbrains YouTrack 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
YouTrack's notification signature mechanism failed to properly validate the authenticity or uniqueness of notification signatures, allowing attackers to capture and replay a previously valid signature to impersonate users. The vulnerability requires network-level access to intercept notifications but does not require prior authentication or user interaction. An attacker who obtains a valid notification signature can use it repeatedly to authenticate as the target user and gain full account access.
Affected products
- JetBrains YouTrack before 2026.2.19197
Timeline
- 2026-09-30: disclosed