Vulnerability in Fit2cloud Jumpserver
CVE-2026-31864
JumpServer is an open source bastion host and an operation and maintenance security audit system. a Server-Side Template Injection (SSTI) vulnerability exists in JumpServer's Applet and VirtualApp upload functionality. This vulnerability can only be exploited by users with administrative privileges (Application Applet Management or Virtual Application Management permissions). Attackers can exploit this vulnerability to execute arbitrary code within the JumpServer Core container. The vulnerability arises from unsafe use of Jinja2 template rendering when processing user-uploaded YAML configuration files. When a user uploads an Applet or VirtualApp ZIP package, the manifest.yml file is rendered through Jinja2 without sandbox restrictions, allowing template injection attacks.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.005 (43.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 44th percentile — 43.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
- Fit2cloud Jumpserver
- Jumpserver — versions < 3.10.22, >= 4.0.0, < 4.10.16
Weakness classification (CWE)
References
- github.com/jumpserver/jumpserver/security/advisories/GHSA-qx8h-rx2j-j5wc (Patch, Vendor Advisory)
- github.com/jumpserver/jumpserver/pull/16608 (Issue Tracking)
Frequently asked questions
- What is CVE-2026-31864?
- CVE-2026-31864 is a medium-severity vulnerability in Fit2cloud Jumpserver, classified under Improper Neutralization of Special Elements Used in a Template Engine. CVSS score: 6.8/10. Published 2026-03-13.
- How severe is CVE-2026-31864?
- Medium severity. CVSS v3 base score is 6.8 out of 10.