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TI-2026-74984 Aliases CVE-2026-55240

Remote code execution in Tianji through survey template rendering

Priority HIGH 74CWE-1336Published · Updated

Key facts

Attack vector
Network
Privileges required
High
User interaction
None
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-1336.

Summary

Tianji before 1.31.29 is an open source analytics and uptime monitoring platform. Survey and monitor notification templates are rendered by lodash template() with the default evaluate pattern enabled, so a stored evaluate block runs as server-side JavaScript (CWE-1336). A workspace administrator can store such a block, and an unauthenticated user triggers it by submitting a survey response. This allows command execution, secret disclosure, data modification, or service disruption.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Description from the CNA

Tianji is an open source analytics, uptime monitoring, and server status platform. Prior to 1.31.29, formatString() in src/server/utils/template.ts passes survey feedTemplate and monitor notification templates to lodash template(), while the default evaluate pattern remains enabled. A workspace administrator can store an evaluate block using the <% code %> form, and the public survey.submit endpoint renders a survey template when an unauthenticated user submits a response. The compiled template executes server-side JavaScript in the Tianji Node.js process, allowing command execution, secret disclosure, data modification, or service disruption. This issue is fixed in version 1.31.29.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00748 55th percentileScored 2026-11-07
Fix Fixed tianji (msgbyte): 1.31.29

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
msgbytetianjibefore 1.31.291.31.29Patch availableCNA
  • tianji Vendormsgbyte Affected before 1.31.29 Fixed in 1.31.29 Patch available CNA

Remediation

Upgrade Tianji to version 1.31.29, which fixes this issue.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

  • Fix · CNA tianji (msgbyte) Fixed in 1.31.29

Timeline

  1. 2026-10-16 Threatist record created from CVE-2026-55240
  2. 2026-10-28 CISA SSVC decision points changed
  3. 2026-10-28 Priority changed: MEDIUM → HIGH
  4. 2026-10-29 EPSS moved to the 50th–90th percentile

References

Other 3

  • TI-2026-74983 SQL injection in Tianji analytics queries via timezone parameter CVSS 3.1HIGH 8.8

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences