CVE-2026-57857
CVE-2026-57857 — Flow Payment Plugin for WordPress Reflected Cross-Site Scripting via error_message Parameter
The Flow Payment plugin for WordPress (flow.cl) version 3.0.8 is vulnerable to reflected cross-site scripting on the WooCommerce checkout page. When the plugin handles an order cancellation, the error_message GET parameter is passed directly to wc_add_notice() in flowpayment-fl.php (lines 57-58) without input sanitization (for example sanitize_text_field()) or output escaping (for example esc_html()) before being rendered in the checkout notice HTML. An unauthenticated attacker can craft a URL containing a JavaScript payload in the error_message parameter (for example /checkout/?add-to-cart={product-id}&cancel_order=true&error_message={payload}); when a victim with an active WooCommerce checkout session follows the link, the payload executes in the victim's browser in the origin of the WordPress site.
Published Updated Sources: cvelistV5, VulnCheck
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.
Exploitation
Unreported
no source claims exploitation
EPSS
0%
chance of exploitation in 30 days
CVSS base
4.3
MEDIUM
CISA SSVC assessment
Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.
Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script all four kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component
Affected scope
The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.
Vendors (1)
Products (1)
Every base score collected
Sources score independently and disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Source |
|---|---|---|---|---|---|
| 4.3 | CVSS 3.1 | MEDIUM | — | — | cvelistV5 |
Weakness & attack patterns
- CWE-79
Detection
Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.
- Search application, proxy, and WAF logs for requests touching /checkout/?add-to-cart=.
References
2 on the record
Elsewhere on this site
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.