CVE-2026-109396 Thelia CVE debrief

Who should care

Defenders responsible for Thelia installations, administrators of affected systems, and security teams should assess exposure and prioritize verification and remediation. They should review user input restrictions, monitor for suspicious activity, and verify Thelia installations to prevent potential CSV formula injection attacks.

Why it matters

Thelia CSV formula injection vulnerability requires verification and remediation to prevent potential data manipulation or unauthorized actions.

• Potential execution of formulas in administrator's spreadsheet application
• Possible data manipulation or unauthorized actions
• Verification of Thelia installations and user input restrictions required
• Remediation priority for affected systems

Technical summary

Thelia before 3.1.2 and 3.2.x before 3.2.1 contains a CSV formula injection vulnerability that allows unauthenticated visitors to inject spreadsheet formulas by supplying crafted registration, checkout, or newsletter fields. Attackers can submit names, addresses, or phone values starting with =, +, -, or @ that CSVSerializer exports verbatim, executing formulas in the administrator's spreadsheet application. This vulnerability requires verification and remediation to prevent potential data manipulation or unauthorized actions.

Defensive priority

Defenders should prioritize verifying and updating Thelia installations to prevent potential CSV formula injection attacks.

Recommended defensive actions

• Verify Thelia installations for version 3.1.2 or 3.2.1 and update if necessary
• Review and restrict user input for registration, checkout, and newsletter fields
• Monitor for suspicious activity in spreadsheet applications
• 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
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability, but limited information is available on potential exploitation or affected systems. Defenders should verify Thelia installations, review user input restrictions, and monitor for suspicious activity. The vulnerability allows unauthenticated visitors to inject spreadsheet formulas by supplying crafted registration, checkout, or newsletter fields. Supplied names, addresses, or phone values starting with =, +, -, or @ are exported verbatim by CSVSerializer, executing in

Sources and 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.