What is CVE-2021-46871?

CVE-2021-46871 is a medium-severity vulnerability in Phoenixframework Phoenix HTML, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2023-01-10.

How severe is CVE-2021-46871?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Phoenixframework Phoenix HTML

CVE-2021-46871

tag.ex in Phoenix Phoenix.HTML (aka phoenix_html) before 3.0.4 allows XSS in HEEx class attributes.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2023-01-10 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.004 (33.9th percentile), scored 2026-10-12.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 34th percentile — 33.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Phoenixframework Phoenix HTML

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

github.com/advisories/GHSA-j3gg-r6gp-95q2 (Patch, Third Party Advisory)
github.com/phoenixframework/phoenix_html/commit/62a0139fb716bcdce697f6221244bd8… (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-46871?: CVE-2021-46871 is a medium-severity vulnerability in Phoenixframework Phoenix HTML, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2023-01-10.
How severe is CVE-2021-46871?: Medium severity. CVSS v3 base score is 6.1 out of 10.