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JumpServer EUVDEUVD-2026-60468

| CVE-2026-44845 MEDIUM
Improper Neutralization of Special Elements Used in a Template Engine (CWE-1336)
2026-08-17 security-advisories@github.com
6.7
CVSS 3.1 · Vendor: github
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Authenticate as JumpServer admin with Applet Host permissions
  2. Delivery
    Inject Jinja2 expression into IP/Host or Core Service Address field
  3. Exploit
    Save malicious Applet Host configuration
  4. Execution
    Trigger Applet Host deployment workflow
  5. Persist
    Ansible evaluates injected Jinja2 template from inventory data
  6. Impact
    Execute arbitrary OS commands as JumpServer service account on control node

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V1 - Encoding and Sanitization Template injection prevention
Exploitation Conditions

Exploitation requires an active JumpServer account with administrator-level privileges and specifically the 'Applet Host management and deployment' permission assigned. The attacker must navigate the Applet Host creation or editing workflow and supply a malicious Jinja2 expression in the IP/Host field or Core Service Address field, and then initiate an Applet Host deployment action to cause Ansible to evaluate the expression. Exploitation is limited by the following factors: the account must hold the elevated Applet Host deployment permission (not a default user role); the attacker must actively trigger a deployment operation, meaning the injection is not passively evaluated; and the command executes as the JumpServer service account, whose privilege level on the host OS varies by deployment. No network-external unauthenticated attack path exists - access to the JumpServer administrative web interface with the correct role assignment is a hard prerequisite.

Impact

CVSS 6.7 with PR:H correctly reflects that exploitation is gated behind a high-privilege account with specific Applet Host deployment permissions, which substantially reduces the attack surface compared to unauthenticated or low-privilege flaws. However, the NVD-assigned I:L metric appears inconsistent with arbitrary command execution on the control node - writing files, installing backdoors, or pivoting to managed bastion targets all constitute high integrity impact; this metric warrants vendor clarification. No EPSS score was provided in the input data. The absence of both a CISA KEV entry and confirmed public POC code means there is no evidence of opportunistic or widespread exploitation at this time. Real-world priority is elevated in environments where multiple teams share JumpServer admin access or where role segregation is weak - a malicious or compromised admin with Applet Host permissions can silently compromise the entire bastion infrastructure. In strictly controlled single-admin deployments the practical risk is lower, but the potential lateral reach to all managed assets via the control node makes this a high-priority patch regardless of the moderate base score.

Exploit ScenarioDerived

A JumpServer administrator with Applet Host deployment rights navigates to the Applet Host management interface and submits a crafted IP/Host value containing a Jinja2 payload such as a subprocess invocation or file-write expression. When the administrator then triggers deployment, Ansible parses the inventory data containing the injected field and evaluates the template expression in the context of the JumpServer service account, executing the embedded command on the control node. No public POC has been confirmed, but the injection surface is well-understood from the Ansible and Jinja2 SSTI class of vulnerabilities.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.5% exploitation probability (EPSS)

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AnalysisAIv1 – Aug 17, 2026

Server-side template injection in JumpServer prior to 4.10.17 enables an authenticated administrator with Applet Host management and deployment permissions to plant Jinja2 expressions in the IP/Host or Core Service Address fields, which Ansible then evaluates as live template expressions during Applet Host deployment, yielding arbitrary OS command execution on the JumpServer control node. The patch was released in v4.10.17, confirmed via the GitHub release tag, and no public exploit code or CISA KEV entry has been identified at time of analysis. Because the control node manages downstream bastion targets, a successful exploit has blast radius well beyond the JumpServer process itself.

RemediationAI

Upgrade JumpServer to version 4.10.17 or later; this is the vendor-confirmed fix and is available at https://github.com/jumpserver/jumpserver/releases/tag/v4.10.17. The upstream fixes are spread across PRs #16749 (https://github.com/jumpserver/jumpserver/pull/16749) and #16886 (https://github.com/jumpserver/jumpserver/pull/16886) and commit cc57ba0de5f6015746fae11cfc62402b11618e59. If an immediate upgrade is not possible, the most effective compensating control is to audit and restrict the 'Applet Host management and deployment' permission so it is held only by a minimal set of fully trusted administrators; removing this permission from all but one or two accounts directly eliminates the ability to trigger the vulnerable code path. As an additional layer, network egress from the JumpServer control node to attacker-controlled infrastructure can be restricted via firewall rules to limit post-exploitation reach, though this does not prevent the command execution itself. No other specific workarounds have been documented by the vendor.

Affected VersionsENISA

jumpserver < 4.10.17

Affected Packages

euvd jumpserver fix: 4.10.17

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

JumpServer uses Ansible to automate Applet Host provisioning; Ansible's inventory and playbook engine processes fields such as ansible_host using the Jinja2 templating engine. CWE-1336 (Improper Neutralization of Special Elements Used in a Template Engine) captures the root cause: the IP/Host and Core Service Address fields accepted by the Applet Host deployment workflow were not sanitized before being embedded in Ansible inventory or playbook variables, allowing an attacker-controlled Jinja2 expression to reach the template evaluation stage. The commit at cc57ba0 and PRs #16749 and #16886 address the problem by adding a validate_account_username utility with a configurable forbidden-characters set and applying it across serializers, connection-token creation, and virtual account resolution - indicating that multiple input paths shared the same unsanitized-input pattern. The Ansible execution context typically runs with the OS-level privileges of the JumpServer service account, which on many deployments carries broad access to managed hosts.

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Severity by source

Vendor (github) PRIMARY 6.7 MEDIUM
AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:L/A:H
vuln.today AI 9.1 CRITICAL

PR:H confirmed by description; S:C and I:H reflect that arbitrary command execution on the bastion control node inherently extends impact to all managed downstream assets, making I:L implausible.

3.1 AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
4.0 AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Primary rating from Vendor (github).

CVSS VectorVendor: github

Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
High

Lifecycle Timeline

2
Patch available
Aug 17, 2026 - 22:03 EUVD
CVE Published
Aug 17, 2026 - 21:16 cve.org
MEDIUM 6.7

DescriptionCVE.org

JumpServer is an open source bastion host and an operation and maintenance security audit system. Prior to 4.10.17, an authenticated administrator with Applet Host management and deployment permissions can inject Jinja2 expressions into the IP/Host field or Core Service Address field, causing Ansible to evaluate ansible_host inventory data or playbook variables during Applet Host deployment and execute arbitrary commands on the JumpServer control node. This issue is fixed in version 4.10.17.

Threat Intelligence Overview

EPSS Score
0.5%
Top 59% exploitable
Prevalence
Medium
popular open source bastion host, strong footprint in Asia-Pacific enterprise
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.5%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
Poc
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

35
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +34
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Code Injection CRITICAL

Code injection occurs when an application accepts user input and passes it directly into a language interpreter or evaluator without proper sanitization.

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