CVE-2022-31103

Improper handling of CSS at-rules in lettersanitizer

7.5 HighFix available

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, therefore everyone using react-letter is also at risk. The problem has been patched in version 1.0.2.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: None

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: High

Exploit likelihood

1.53%Up 0.6 points since Jun 28, 2022

What each source reports

CVE List Score used 7.5

Improper handling of CSS at-rules in lettersanitizer

Record: CVE-2022-31103
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-754
Updated: 2026-11-02

EUVDEUVD-2022-5983 7.5

Record: EUVD-2022-5983
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated: 2026-11-02

GitHub AdvisoriesGHSA-7r3r-gq8p-v9jj 7.5

Improper handling of CSS at-rules in lettersanitizer

Impact

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, therefore everyone using react-letter is also at risk.

Patches

The problem has been patched in version 1.0.2.

Workarounds

There is no workaround besides upgrading.

References

The issue was originally reported in the react-letter repository: https://github.com/mat-sz/react-letter/issues/17

For more information

If you have any questions or comments about this advisory:

Open an issue in lettersanitizer
Email me at [email protected]

Record: GHSA-7r3r-gq8p-v9jj
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-754
Updated: 2026-11-02

NVD 7.5

Record: CVE-2022-31103
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0: 5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness: CWE-754
Updated: 2026-11-02

OSV 7.5

Improper handling of CSS at-rules in lettersanitizer

Record: CVE-2022-31103
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-754
Updated: 2026-11-02

OSVGHSA-7r3r-gq8p-v9jj 7.5

Improper handling of CSS at-rules in lettersanitizer

Impact

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, therefore everyone using react-letter is also at risk.

Patches

The problem has been patched in version 1.0.2.

Workarounds

There is no workaround besides upgrading.

References

The issue was originally reported in the react-letter repository: https://github.com/mat-sz/react-letter/issues/17

For more information

If you have any questions or comments about this advisory:

Open an issue in lettersanitizer
Email me at [email protected]

Record: GHSA-7r3r-gq8p-v9jj
CVSS 3.1: 7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-754
Updated: 2026-11-02

Affected products

Affected packages

Affected packages
Package	Affected	Fixed
`lettersanitizer` npm	before 1.0.2	1.0.2

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2022-31103 is a high vulnerability (CVSS 7.5) in Lettersanitizer Project Lettersanitizer, published June 23, 2022. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.53%, the 74th percentile. Fixed in lettersanitizer 1.0.2.