Security readout for executives and security teams
Plain-English summary
CVE-2022-31103 can make browser-based email rendering fail or hang when vulnerable lettersanitizer versions process certain CSS at-rules. The impact is availability, not data theft or code execution based on the supplied sources. Organizations using lettersanitizer below 1.0.2, including via react-letter, should update promptly.
Executive priority
Patch in the next normal security release cycle, faster for customer-facing email viewers or support tools. The business risk is service disruption from crafted content, not confirmed compromise. Because the fix is a version upgrade, remediation should be low complexity for most teams.
Technical view
lettersanitizer, a DOM-based HTML email sanitizer for in-browser rendering, mishandles CSS @keyframes at-rules. Versions below 1.0.2 are vulnerable to denial of service. The CVSS 3.1 score is 7.5 because the issue is network-reachable, low complexity, unauthenticated, and affects availability only.
Likely exposure
Exposure is likely in web applications that render untrusted HTML email using lettersanitizer below 1.0.2. Applications using react-letter may be affected transitively because react-letter depends on lettersanitizer. The source bundle does not identify affected hosted services or broader product integrations.
Exploitation context
The provided sources describe denial of service from CSS at-rule handling. CISA KEV status is false in the bundle, and no cited source here confirms active exploitation. Treat exploitability as plausible from untrusted email content, but do not assume known exploitation without additional evidence.
Researcher notes
Evidence is strongest for affected versions, impact type, and fixed version. The bundle does not provide detailed root-cause analysis beyond improper CSS at-rule handling, nor does it include confirmed exploitation. Avoid claiming confidentiality or integrity impact because CVSS marks both as none.
Mitigation direction
- Upgrade lettersanitizer to version 1.0.2 or later.
- Update react-letter dependency trees that pull vulnerable lettersanitizer versions.
- Refresh lockfiles so transitive dependency resolution actually uses the patched version.
- Check the GitHub advisory for any newer vendor guidance.
- Prioritize applications that render untrusted email or user-supplied HTML.
Validation and detection
- Review package manifests and lockfiles for lettersanitizer below 1.0.2.
- Check whether react-letter is present in frontend dependency trees.
- Confirm deployed builds include the patched lettersanitizer version.
- Review monitoring for sanitizer-related browser crashes or rendering failures.
- Verify untrusted email HTML rendering paths use the updated dependency.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
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CWE-754: Exact CWE lookup
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Open ATT&CK lookupCVE-2022-31103 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/mat-sz/lettersanitizer/security/advisories/GHSA-7r3r-gq8p-v9jjCVE reference · x_refsource_CONFIRM
- https://github.com/mat-sz/react-letter/issues/17CVE reference · x_refsource_MISC
- https://github.com/mat-sz/lettersanitizer/commit/96d3dfe2ef0465d47324ed4d13e91ba0816a173fCVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Check for Unusual or Exceptional Conditions
Improper Check for Unusual or Exceptional Conditions represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.