CVE-2026-100869 Sylius CVE debrief

Who should care

Defenders responsible for e-commerce platforms, particularly those using Sylius, should assess their exposure and prioritize patching to prevent potential financial loss. This includes verifying the versions of Sylius in use, applying patches, and monitoring payment gateway transactions for suspicious activity. Additionally, defenders should review compensating controls for exposed systems while remediation is scheduled and verified, and track exceptions,

Why it matters

CVE-2026-100869 is a high-severity vulnerability in Sylius that allows attackers to trigger refunds on completed orders, potentially leading to financial loss. Defenders responsible for e-commerce platforms, particularly those using Sylius, should assess their exposure and prioritize patching.

• Financial loss due to unauthorized refunds
• Potential disruption to payment gateway transactions
• Need for verification of Sylius versions in use
• Importance of restricting access to order tokens

Technical summary

The vulnerability in Sylius allows attackers with order tokens to submit arbitrary payment actions, including refunds, which can lead to financial loss. This issue affects Sylius versions before 2.1.16 and 2.2.9. The vulnerability has a CVSS score of 8.2 and is considered HIGH severity. The CVE record and NVD entry provide details on the vulnerability, including its description, CVSS score, and affected versions. There are no known exploits or reports of this vulnerability being used in attacks. Defenders should prioritize verifying the versions of Sylius in use and applying the necessary patches to prevent potential financial loss.

Defensive priority

Defenders should prioritize verifying the versions of Sylius in use and applying the necessary patches to prevent potential financial loss.

Recommended defensive actions

• Verify the version of Sylius in use and apply patches to prevent potential financial loss.
• Restrict access to order tokens to prevent unauthorized access.
• Monitor payment gateway transactions for suspicious activity.
• 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 NVD entry provide details on the vulnerability, including its description, CVSS score, and affected versions. The vulnerability is caused by a lack of restriction on payment request actions in the Shop API endpoint, allowing customers to trigger refunds on completed orders. The CVE record was published on 2026-09-27T13:16:38.100Z and has not been modified since then. There are no known exploits or reports of this vulnerability being used in attacks.

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.