tag.ex in Phoenix Phoenix.HTML (aka phoenix_html) before 3.0.4 allows XSS in HEEx class attributes.
Priority LOW 28CWE-79Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and GitHub. Impact type from CWE-79.
Summary
tag.ex in Phoenix Phoenix.HTML (aka phoenix_html) before 3.0.4 allows XSS in HEEx class attributes.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00434 37th percentileScored 2026-11-07
Fix Fixed phoenix_html (npm): 3.0.4phoenix_html (Hex): 3.0.4
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
| — | phoenix_html (npm) | before 3.0.4 | 3.0.4 | Patch available | GHSA-5g2h-9x5v-5h3x |
| — | phoenix_html (Hex) | before 3.0.4 | 3.0.4 | Patch available | GHSA-5g2h-9x5v-5h3x |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
- phoenix_html (npm) Vendor— Affected before 3.0.4 Fixed in 3.0.4 Patch available GHSA-5g2h-9x5v-5h3x
- phoenix_html (Hex) Vendor— Affected before 3.0.4 Fixed in 3.0.4 Patch available GHSA-5g2h-9x5v-5h3x
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:phoenixframework:phoenix_html:*:*:*:*:*:*:*:* | before 3.0.4 | Vulnerable | phoenixframework |
- cpe:2.3:a:phoenixframework:phoenix_html:*:*:*:*:*:*:*:* Versions before 3.0.4 Vulnerable ·phoenixframework
Remediation
- Fix · GHSA-5g2h-9x5v-5h3x phoenix_html (npm) Fixed in 3.0.4 Advisory →
- Fix · GHSA-5g2h-9x5v-5h3x phoenix_html (Hex) Fixed in 3.0.4 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2021-46871
- 2026-10-03 Alias added: GHSA-5g2h-9x5v-5h3x
References
Sources
- CVE-2021-46871 · CVE Program
- CVE-2021-46871 · NVD
- FIRST EPSS
- GHSA-5g2h-9x5v-5h3x · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences