CVE-2022-31103

Improper handling of CSS at-rules in lettersanitizer

HIGH
7.5
CVSS Score
Published: June 27, 2022 at 10:20 PM UTC
Updated: June 17, 2026 at 04:44 AM UTC
2 products affected across 2 vendorsLettersanitizerProject Lettersanitizer

Using lettersanitizer by mat-sz?

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Severity
HIGH7.5
Exploit prediction
EPSS 2%
SSVC
No known exploit

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 1.0.2
Affected range stops below 1.0.2, so it looks safe — our inference, not a vendor statement
v < 1.0.2
Affected range stops below 1.0.2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-754

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