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VulnerabilityCVE-2026-43927Published 2026-07-06

CVE-2026-43927 — FOSSBilling

medium (derived)

As of 2026-07-07, CVE-2026-43927 is a Medium-severity (band derived from the CVSS v4.0 score, not stated by the CNA) vulnerability in FOSSBilling, CVSS v4.0 6.9, EPSS 0.2% (12.4th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-43927 as of 2026-07-07; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

CVSS v4.0
6.9/10Medium (derived)
EPSS
0.2%Higher than 12.4% of scored CVEs
CISA KEV
NoNot in the KEV catalog
Tracked threats
0None linked yet
Priority
3.9/10Threadlinqs triage score
Published
Updated 2026-07-07
CVSS v4.0 6.9 (Medium, derived from score) · EPSS 0.2% (higher than 12.4% of all scored CVEs) · Priority 3.9/10 · Published 2026-07-06

Last updated:

What is CVE-2026-43927?

FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.0, a race condition in the cart checkout flow allows an authenticated client to apply a promo code beyond its configured maximum uses. By sending concurrent checkout requests before any single request completes the usage increment, a client can obtain unlimited discounted or free orders from a single-use or limited-use promo code. Version 0.8.0 patches the issue. Some workarounds are available. Disable promo codes entirely until a patch is available or monitor the `promo` table for `used` values exceeding `maxuses` and manually review affected orders.

The record classifies CVE-2026-43927 under weakness class CWE-367. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 91 days ago.

Severity and exploitation probability

CVSS v4.0 base score
6.9 — Medium (derived from score)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
EPSS (FIRST)
0.2% probability of exploitation in the next 30 days, higher than 12.4% of all scored CVEs
CISA KEV
Not listed in the CISA Known Exploited Vulnerabilities catalog
Threadlinqs priority
3.9/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
Published
2026-07-06, last modified 2026-07-07

Is CVE-2026-43927 being exploited?

It currently carries a trending score of 33 in the Threadlinqs vulnerability feed.

Affected products and versions

How to fix CVE-2026-43927

No vendor patch reference has been recorded for CVE-2026-43927 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

Threat activity tracking CVE-2026-43927

No threat campaign in the Threadlinqs corpus currently references CVE-2026-43927, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

Sources

Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.

Vendor advisory and patch