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.

AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CWE-74

https://cna.erlef.org/cves/CVE-2026-68747.html

https://github.com/rrrene/html_sanitize_ex/commit/0b9f9ad63a7529d4f2c3c1134c371adc3e654308

https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-87v2-pfhj-r5x7

https://osv.dev/vulnerability/EEF-CVE-2026-68747

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