CVE-2024-34078 html-sanitizer allows arbitrary HTML present after sanitization because of unicode normalization

2024-05-0614:48:47

CWE-79

GitHub_M

www.cve.org

html-sanitizer

allowlist-based

html cleaner

keep_typographic_whitespace=false

nfkc form

chevrons

sanitization

cve-2024-34078

unicode normalization

2.4.2 fix

6.1 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

CHANGED

Confidentiality Impact

LOW

Integrity Impact

LOW

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

0.0004 Low

EPSS

Percentile

9.0%

JSON

html-sanitizer is an allowlist-based HTML cleaner. If using keep_typographic_whitespace=False (which is the default), the sanitizer normalizes unicode to the NFKC form at the end. Some unicode characters normalize to chevrons; this allows specially crafted HTML to escape sanitization. The problem has been fixed in 2.4.2.

CNA Affected

[
  {
    "vendor": "matthiask",
    "product": "html-sanitizer",
    "versions": [
      {
        "version": "< 2.4.2",
        "status": "affected"
      }
    ]
  }
]