bluemonday before 1.0.5 allows XSS because certain Go lowercasing converts an uppercase…
Priority LOW 29CWE-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 · NVD. Fix status from CNA and GitHub. Impact type from CWE-79.
Summary
bluemonday before 1.0.5 allows XSS because certain Go lowercasing converts an uppercase Cyrillic character, defeating a protection mechanism against the "script" string.
Why it matters now
EPSS 0.00929 60th percentileScored 2026-11-07
Fix Fixed github.com/microcosm-cc/bluemonday (Go): 1.0.5
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
| — | github.com/microcosm-cc/bluemonday (Go) | before 1.0.5 | 1.0.5 | Patch available | GHSA-3x58-xr87-2fcj |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
- github.com/microcosm-cc/bluemonday (Go) Vendor— Affected before 1.0.5 Fixed in 1.0.5 Patch available GHSA-3x58-xr87-2fcj
Remediation
- Fix · GHSA-3x58-xr87-2fcj github.com/microcosm-cc/bluemonday (Go) Fixed in 1.0.5 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 1 product
- Red Hat Advanced Cluster Management for Kubernetes 2
Timeline
- 2026-10-02 Threatist record created from CVE-2021-29272
- 2026-10-03 Alias added: GHSA-3x58-xr87-2fcj
References
Advisory 3
More Microco Bluemonday vulnerabilities
- TI-2021-18856 The bluemonday sanitizer before 1.0.16 for Go, and before 0.0.8 for Python (in… CVSS 3.1CRITICAL 9.8
Sources
- CVE-2021-29272 · CVE Program
- CVE-2021-29272 · NVD
- FIRST EPSS
- GHSA-3x58-xr87-2fcj · GitHub Advisory Database · CC BY 4.0
- CVE-2021-29272 · Red Hat security data · CC BY 4.0
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