Affected versions: ≥ 6.0.0 and < 6.6.6
Full advisory: our disclosure post
CVE-2026-102803MediumCVSS 6.0CVE published 10 November 2026Added to mySites.guru 9 November 2026
J2Commerce (com_j2commerce) 6.0.0 to 6.6.5 - CVE-2026-102803 Gift Voucher and Single-Use Coupon Reuse (checkout race condition)
J2Commerce 6.0.0 to 6.6.5 (listed in the CVE record as J2Store 6.0.0 - 6.6.5) let a logged-in customer redeem one gift voucher, or one single-use coupon, on more than one order. By opening several checkout sessions and taking each to the confirm step before submitting any of them, every order saw the voucher's full balance or the coupon's unused slot, because the balance and usage checks only counted orders that had already left the New state. CVSS 4.0 score 6.0 (Medium). Fixed in J2Commerce 6.6.6: update to 6.6.6 or later. This is the J2Commerce 6 component (com_j2commerce), not the older J2Store 3.x/4.x line (com_j2store).
Is my site affected?
- Affected
- J2Commerce from 6.0.0 up to but not including 6.6.6
- Fixed in
- 6.6.6
- What to do
- Update J2Commerce to 6.6.6 or later.
How CVE-2026-102803 is scored
The base metrics as Joomla CNA published them, and what each one means for a site running an affected version. Threat and environmental metrics are left out: they describe a moment or a particular install rather than the flaw.
6.0 Medium
CVSS 4.0, scored by Joomla CNACVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:NHow it is reached
- AV:N Attack vector
- Network. Reachable across the internet
- AC:L Attack complexity
- Low. Nothing to work around, it just works
- AT:P Attack requirements
- Present. Needs a particular deployment or race to line up
- PR:L Privileges required
- Low. Any logged-in account will do
- UI:N User interaction
- None. Nobody has to be tricked into anything
What it does to the site
- VC:N Confidentiality
- None. Nothing can be read
- VI:H Integrity
- High. Data and files can be altered at will
- VA:N Availability
- None. The site stays up
What it does beyond the site
- SC:N Confidentiality
- None. Other systems keep their data
- SI:N Integrity
- None. Other systems keep their integrity
- SA:N Availability
- None. Other systems stay up
Timeline
- 9 November 2026mySites.guru check added for J2Commerce (from 6.0.0 up to but not including 6.6.6)
- 10 November 2026CVE-2026-102803 record published by its CNA
- 10 November 2026We published: J2Commerce 6.6.6 Stops One Gift Voucher Paying for Several Orders
Rule details
Our disclosure post
Other vulnerabilities in J2Commerce
Updating for CVE-2026-102803 alone can leave a site on a release another rule still matches. These are the other flaws we check for in the same extension.
J2Commerce
Latest safe version: 6.6.6
References
- CVE-2026-102803 on cve.org (the official CVE record)
- CVE-2026-102803 in the NIST National Vulnerability Database
- J2Commerce 6.6.6 Stops One Gift Voucher Paying for Several Orders
CVE-2026-102803 questions
Which versions are affected by CVE-2026-102803?
CVE-2026-102803 affects J2Commerce from 6.0.0 up to but not including 6.6.6. The fix is in 6.6.6.
How do I fix CVE-2026-102803?
Update J2Commerce to 6.6.6 or later. Then confirm the installed version on the Joomla administrator's Extensions: Manage screen.
How severe is CVE-2026-102803?
Joomla CNA scores it 6.0 (Medium) under CVSS 4.0. In plain terms: reachable across the internet, any logged-in account will do and nobody has to be tricked into anything.
Running an affected version on a site you manage?
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This check is part of the mySites.guru Joomla vulnerability scanner, which reads every installed extension's version on each audit. Browse the rest of the Joomla vulnerability database.
Rules current as of 10 November 2026.