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CVE-2026-59791 JetBrains CVE debrief

A low-severity vulnerability was found in JetBrains YouTrack before version 2026.2.17012. The issue allows for CSS injection via Mermaid diagram rendering. This type of vulnerability can lead to potential styling or rendering issues within the application. Users of JetBrains YouTrack should apply the patch to prevent potential CSS injection attacks. The CVE record was published on 2026-07-10T15:16:48.110Z and has not been modified since then. The Common Vulnerability Scoring System (CVSS) score is 3.5, indicating a low severity.

Vendor
JetBrains
Product
YouTrack
CVSS
LOW 3.5
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-10
Original CVE updated
2026-07-10
Advisory published
2026-07-10
Advisory updated
2026-07-10

Who should care

Users of JetBrains YouTrack before version 2026.2.17012 should apply the patch to prevent potential CSS injection attacks. This includes administrators and security teams responsible for maintaining and securing instances of YouTrack. Additionally, developers and operators who work with Mermaid diagrams in YouTrack should be aware of this vulnerability and take necessary precautions.

Technical summary

The vulnerability, CVE-2026-59791, is a CSS injection issue in JetBrains YouTrack before version 2026.2.17012. It occurs via Mermaid diagram rendering. The Common Vulnerability Scoring System (CVSS) score is 3.5, indicating a low severity. The CVSS vector is CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N. This issue can be mitigated by applying the patch to upgrade to version 2026.2.17012 or later.

Defensive priority

Low priority, but recommended to patch for defense-in-depth.

Recommended defensive actions

  • Apply the patch to upgrade JetBrains YouTrack to version 2026.2.17012 or later.
  • Review and monitor Mermaid diagram rendering in YouTrack for suspicious activity.
  • Consider implementing additional security measures for YouTrack, such as input validation and content security policy.
  • Review compensating controls for exposed systems while remediation is scheduled and verified.
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The CVE record and NVD entry provide limited information about the vulnerability. Further investigation and verification are recommended. The vulnerability allows for CSS injection via Mermaid diagram rendering in JetBrains YouTrack before version 2026.2.17012. Users should verify their deployments and apply patches accordingly. Evidence is limited, and defenders should review the official advisory for affected scope and severity.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-59791 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-59791

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-59791 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-59791

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.