Time-of-check Time-of-use (TOCTOU) Race Condition in Sylius - CVE-2026-31824
Published: April 27, 2026
Vulnerability identifier: #VU128220
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N/E:U/U:Amber
CVE-ID: CVE-2026-31824
CWE-ID: CWE-367
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Sylius
Affected software:
Sylius
Sylius
Detailed vulnerability description
The vulnerability allows a remote attacker to bypass promotion and coupon usage limits.
The vulnerability exists due to a time-of-check time-of-use race condition in promotion usage limit enforcement when completing orders through concurrent API requests. A remote attacker can send simultaneous PATCH requests to redeem a limited-use promotion or coupon multiple times.
The same race condition affects the global promotion usage counter, the global coupon usage counter, and the per-customer coupon redemption count.
How to mitigate CVE-2026-31824
Install security update from vendor's website.