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

Published · last modified .

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.

EPSS exploit prediction

EPSS: 0.003 (20.7th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 21st percentile — 20.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-31821: held from 0.002 to 0.003.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

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

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.