CVE-2026-68749highCWE-1333

CVE-2026-68749: high-severity vulnerability in rrrene html_sanitize_ex

Quadratic regex backtracking in the html_sanitize_ex CSS scrubber allows CPU-exhaustion denial of service

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21Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 8.2epss 0.8%
from disclosure to weapon7 days
Published on NVDAug 6
1st PoC+7d
Inefficient Regular Expression Complexity vulnerability in the CSS scrubber in rrrene html_sanitize_ex allows an unauthenticated remote attacker to exhaust server CPU via a long CSS declaration in sanitized HTML. The declaration regex in HtmlSanitizeEx.Scrubber.CSS.scrub/1 matches the property name with an unbounded greedy [-\w]+ followed by a mandatory :, so a long run of word characters not followed by a colon makes the engine give back one character at a time and retry the colon at every start offset. The work is quadratic in the length of the run, and no length cap is applied to the CSS handed to the scrubber. An 80 KB <style> body costs roughly 2.4 seconds of scheduler time, so a few concurrent requests saturate the BEAM scheduler pool and make the application unresponsive. The impact is CPU exhaustion only. Nothing is read, modified or disclosed. This issue affects html_sanitize_ex: from 0.3.1 before 1.4.5 and from 1.5.0-rc.0 before 1.5.3.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Affected products
rrrene · html_sanitize_ex
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Related CVEs — rrrene html_sanitize_ex

In the same product, most dangerous first.

CVE-2026-68750HIGHQuadratic sibling re-flattening in the html_sanitize_ex traversal engine allows CPU-exhaustion denial of serviceEPSS 0.8%CVE-2026-66829LOWhtml_sanitize_ex HTML5 scrubber keeps attacker-supplied meta refresh, allowing forced cross-origin redirectionEPSS 0.6%CVE-2026-66843LOWhtml_sanitize_ex HTML5 scrubber keeps attacker-supplied `<object>` elements, allowing untrusted content embeddingEPSS 0.5%CVE-2026-68747LOWCSS sanitizer allowlist bypass in html_sanitize_ex via non-declaration inputEPSS 0.4%CVE-2026-66370MEDIUMhtml_sanitize_ex HTML5 scrubber keeps attacker-supplied form-association attributes, allowing form hijackingEPSS 0.4%