How severe is CVE-2021-3646?

CVE-2021-3646 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-3646 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3646?

CVE-2021-3646 affects Btcpayserver Btcpay Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-3646?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-3646 published?

CVE-2021-3646 was published on 2021-09-10 and last updated on 2026-06-17.

CVE-2021-3646

CVE-2021-3646 is a medium-severity vulnerability in Btcpayserver Btcpay Server with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v2: 4.3
EPSS exploit prediction: 1% (51st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Btcpayserver Btcpay Server
Published: 2021-09-10
Last modified: 2026-06-17

Description

btcpayserver is vulnerable to Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Frequently asked questions

What is CVE-2021-3646?: btcpayserver is vulnerable to Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
How severe is CVE-2021-3646?: CVE-2021-3646 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-3646 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3646?: CVE-2021-3646 affects Btcpayserver Btcpay Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-3646?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-3646 published?: CVE-2021-3646 was published on 2021-09-10 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:btcpayserver:btcpay_server:*:*:*:*:*:*:*:*

More vulnerabilities in Btcpayserver Btcpay Server

CVE-2022-32984 — High (CVSS 7.5): BTCPay Server 1.3.0 through 1.5.3 allows a remote attacker to obtain sensitive information when a public Point of Sale…
CVE-2021-29249 — High (CVSS 7.5): BTCPay Server before 1.0.6.0, when the payment button is used, has a privacy vulnerability.
CVE-2021-29246 — Medium (CVSS 6.7): BTCPay Server through 1.0.7.0 suffers from directory traversal, which allows an attacker with admin privileges to…
CVE-2021-29251 — Medium (CVSS 6.5): BTCPay Server before 1.0.7.1 mishandles the policy setting in which users can register (in Server Settings > Policies).…
CVE-2023-0879 — Medium (CVSS 6.3): Cross-site Scripting (XSS) - Stored in GitHub repository btcpayserver/btcpayserver prior to 1.7.12.
CVE-2023-1149 — Medium (CVSS 5.4): Improper Neutralization of Equivalent Special Elements in GitHub repository btcpayserver/btcpayserver prior to 1.8.0.

All CVEs affecting Btcpayserver Btcpay Server →

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