CVE intelligence and bounded remediation

CVE-2023-36823 — Sanitize is an allowlist-based HTML and CSS sanitizer

High CVSS 7.1

Sanitize is an allowlist-based HTML and CSS sanitizer. Using carefully crafted input, an attacker may be able to sneak arbitrary HTML and CSS through Sanitize starting with version 3.0.0 and prior to version 6.0.2 when Sanitize is configured to use the built-in "relaxed" config or when using a custom config that allows `style` elements and one or more CSS at-rules. This could result in cross-site scripting or other undesired behavior when the malicious HTML and CSS are rendered in a browser. Sanitize 6.0.2 performs additional escaping of CSS in `style` element content, which fixes this issue. Users who are unable to upgrade can prevent this issue by using a Sanitize config that doesn't allow `style` elements, using a Sanitize config that doesn't allow CSS at-rules, or by manually escaping the character sequence `</` as `<\/` in `style` element content.

Severity
High
CVSS
7.1 (3.1)
Published
2023-07-06
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-79

Affected products

  • sanitize_project / sanitize
  • debian / debian_linux / 10.0

Matched remediation archetype

Cross-site scripting and unsafe browser output

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Check exposure

  • Trace reflected, stored, and DOM-derived untrusted values into HTML, attributes, URLs, styles, scripts, and client-side template sinks.
  • Identify affected origins, authenticated user roles, sensitive browser capabilities, and where content is shared across tenants.
  • Review framework escaping, rich-text sanitization, legacy templates, and client-side rendering paths.

Remediate safely

  • Use context-aware framework output encoding and safe DOM APIs; keep untrusted data out of executable contexts.
  • Sanitize intentionally supported markup with a maintained allowlist policy and validate URLs and attributes separately.
  • Update affected rendering components and add tests for every output context using inert sentinel markup.

Authoritative sources

Complete CVE record and remediation plan

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