Improper handling of CSS at-rules in lettersanitizer
Priority MEDIUM 42CWE-754Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub.
Summary
lettersanitizer is a DOM-based HTML email sanitizer for in-browser email rendering. All versions of lettersanitizer below 1.0.2 are affected by a denial of service issue when processing a CSS at-rule `@keyframes`. This package is depended on by [react-letter](https://github.com/mat-sz/react-letter), therefore everyone using react-letter is also at risk. The problem has been patched in version 1.0.2.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.01526 74th percentileScored 2026-11-07
Fix Fixed lettersanitizer (mat-sz): 1.0.2lettersanitizer (npm): 1.0.2
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- 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 |
|---|---|---|---|---|---|
| mat-sz | lettersanitizer | before 1.0.2 | 1.0.2 | Patch available | CNA |
| — | lettersanitizer (npm) | before 1.0.2 | 1.0.2 | Patch available | GHSA-7r3r-gq8p-v9jj |
- lettersanitizer Vendormat-sz Affected before 1.0.2 Fixed in 1.0.2 Patch available CNA
- lettersanitizer (npm) Vendor— Affected before 1.0.2 Fixed in 1.0.2 Patch available GHSA-7r3r-gq8p-v9jj
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:lettersanitizer_project:lettersanitizer:*:*:*:*:*:node.js:*:* | before 1.0.2 | Vulnerable | Lettersanitizer Project |
- cpe:2.3:a:lettersanitizer_project:lettersanitizer:*:*:*:*:*:node.js:*:* Versions before 1.0.2 Vulnerable ·Lettersanitizer Project
Remediation
- Fix · CNA lettersanitizer (mat-sz) Fixed in 1.0.2
- Fix · GHSA-7r3r-gq8p-v9jj lettersanitizer (npm) Fixed in 1.0.2 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2022-31103
- 2026-10-03 Alias added: GHSA-7r3r-gq8p-v9jj
References
Advisory 3
Sources
- CVE-2022-31103 · CVE Program
- CVE-2022-31103 · NVD
- FIRST EPSS
- GHSA-7r3r-gq8p-v9jj · 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