What is CVE-2021-29250?

CVE-2021-29250 is a medium-severity vulnerability in Btcpayserver Btcpay Server, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-05-05.

How severe is CVE-2021-29250?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Btcpayserver Btcpay Server

CVE-2021-29250

BTCPay Server through 1.0.7.0 suffers from a Stored Cross Site Scripting (XSS) vulnerability within the POS Add Products functionality. This enables cookie stealing.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2021-05-05 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.005 (43.5th percentile), scored 2026-10-20.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 43rd percentile — 43.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

Btcpayserver Btcpay Server

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

github.com/btcpayserver/btcpayserver/releases (Third Party Advisory, Release Notes)
blog.btcpayserver.org/vulnerability-disclosure-v1-0-7-0/ (Vendor Advisory)

Frequently asked questions

What is CVE-2021-29250?: CVE-2021-29250 is a medium-severity vulnerability in Btcpayserver Btcpay Server, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2021-05-05.
How severe is CVE-2021-29250?: Medium severity. CVSS v3 base score is 5.4 out of 10.