Live Exposure Defense: From CVE to Confirmed Exposure in 12 Hours – See more

Back
New CVE Detected

CVE-2026-54390 – Unauthenticated SSTI / RCE – JTL Shop 5.2.0 through 5.7.1

Be the first to know when new zero-days emerge:

Subscribe to Email Alerts
Subscribe to RSS Feed

Summary

CVE-2026-54390 is a critical server-side template injection (SSTI) vulnerability in JTL Shop versions 5.2.0 through 5.7.1, caused by unsanitized user-supplied input being passed directly to the Smarty template engine. Rated CVSS 4.0 9.3 CRITICAL and CVSS 3.1 9.8 CRITICAL, the flaw is exploitable by unauthenticated, remote attackers with no user interaction required, enabling sensitive credential theft on all affected versions and full remote code execution (RCE) on versions 5.4.0 and later. JTL Software released patches on June 17, 2026.

Technical details

  • Root cause: User-supplied input — specifically in email subject line processing — is passed to the Smarty template engine without sanitization, permitting injection of arbitrary Smarty template syntax (CWE-1336: Improper Neutralization of Special Elements Used in a Template Engine).
  • Trigger conditions: No authentication, privileges, or user interaction are required. The attack is executable by any network-accessible attacker against an internet-facing shop.
  • Attack vector: Network (AV:N), no credentials required (PR:N), no user interaction (UI:N), low attack complexity (AC:L).
  • Impact — versions 5.2.0–5.7.1 (credential theft): Attackers can read sensitive server-side values including the BLOWFISH_KEY, database host/name/user/password, SMTP and newsletter credentials, FTP and Redis settings, OAuth secrets, and stored SFTP private keys.
  • Impact — versions 5.4.0–5.7.1 (full RCE): Attackers can additionally leverage registered Smarty modifiers (unserialize, file_get_contents) to write a webshell to the web root and execute arbitrary operating system commands as the web server user, achieving complete host compromise.

Affected software

  • JTL Shop 5.2.0 through 5.3.x — credential theft
  • JTL Shop 5.4.0 through 5.7.1 — credential theft and full unauthenticated RCE

Severity

CVSS v3.1 base score: 9.8 CRITICAL
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v4.0 base score: 9.3 CRITICAL
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Mitigation and recommended actions

  • Immediate — upgrade to a patched release:
    • Branch 5.5.x → upgrade to JTL Shop 5.5.4
    • Branch 5.6.x → upgrade to JTL Shop 5.6.2
    • Branch 5.7.x → upgrade to JTL Shop 5.7.2
  • Older installations (5.0.0–5.7.0): Apply JTL’s published back-patch, which covers all 5.x versions that cannot move to the latest point release within their branch.
  • If immediate patching is not feasible: Restrict external network access to shop administration and template configuration endpoints, and monitor the web root for unexpected file creation and outbound connections indicating webshell activity.

IONIX Status

The IONIX research team is tracking ongoing exploitation attempts and recommends immediate patching. Potentially affected assets are outlined in this post.

References

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report

How IONIX’s External Exposure Management Platform Detects and Validates
Zero-Days to Shrink MTTR

1

Map your entire attack surface (continously)

IONIX uses multi-factor discovery methods, including DNS analysis, certificate mapping, metadata inspection, and more, to automatically map every internet-facing asset across your environment. This includes cloud instances, third-party platforms, shadow IT, and even forgotten infrastructure that traditional tools miss.

2

Monitor for new CVEs

Dozens of threat intel feeds using agentic technology are continuously analyzed to detect the appearance of proof-of-concept code, exploit kits, and indicators of active targeting. IONIX goes further by applying AI to proactively evaluate whether emerging vulnerabilities are likely to be exploited, even before PoCs go public.

3

Identify Potential External Exposures

Not all CVEs matter. IONIX filters vulnerabilities by asking attacker-centric questions: Can it be reached from the internet? Does it require authentication? Is it being exploited in the wild? This dramatically reduces noise and focuses teams on threats that can actually be weaponized.

4

Create Safe, Scalable Exploit Validations

IONIX transforms real-world PoCs into safe, non-intrusive test payloads that can be run in production environments without disruption. These simulations are precisely targeted to the systems that are vulnerable, ensuring rapid validation without unnecessary load.

5

Execute Exploit Validations

By combining context about software stack, versioning, exposure status, and reachability, IONIX ensures that only the right payloads are executed against the right assets, maximizing efficiency and minimizing risk.

6

Drive Fast and Actionable Remediation

Results are routed through integrations with ticketing, SOAR, and SIEM tools. Issues are written in plain language, bundled into remediation clusters, and prioritized based on asset criticality, exploitability, and blast radius. This shortens mean time to remediation (MTTR) and empowers teams to act with confidence.

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report
Close

Subscribe to Threat Center RSS

Copy/paste the link below into your preferred RSS reader or follow these instructions to subscribe to Slack alerts.

Open RSS feedSlack setup instructions

Close

Get Real-Time CVE Alerts to Your Email

Be the first to know when new zero-days emerge