Auth bypass in Sylius
CVE-2026-31821
Sylius is an Open Source eCommerce Framework on Symfony. The POST /api/v2/shop/orders/{tokenValue}/items endpoint does not verify cart ownership. An unauthenticated attacker can add items to other registered customers' carts by knowing the cart tokenValue. An attacker who obtains a cart tokenValue can add arbitrary items to another customer's cart. The endpoint returns the full cart representation in the response (HTTP 201). The issue is fixed in versions: 2.0.16, 2.1.12, 2.2.3 and above.
Vulnerability class: Broken Access Control
EPSS: 0.002 (8.1th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.
Affected products
- Sylius — versions >= 2.2.0, < 2.2.3, >= 2.1.0, < 2.1.12, >= 2.0.0, < 2.0.16
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-31821?
- CVE-2026-31821 is a medium-severity vulnerability in Sylius, classified under Missing Authorization. CVSS score: 5.3/10. Published 2026-03-10.
- How severe is CVE-2026-31821?
- Medium severity. CVSS v3 base score is 5.3 out of 10.