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 1.5.3.
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Affected Vendors & Products
References
History
Thu, 06 Aug 2026 16:30:00 +0000
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ssvc
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Thu, 06 Aug 2026 15:30:00 +0000
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| Description | 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 1.5.3. | |
| Title | Quadratic regex backtracking in the html_sanitize_ex CSS scrubber allows CPU-exhaustion denial of service | |
| First Time appeared |
Rrrene
Rrrene html Sanitize Ex |
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| Weaknesses | CWE-1333 | |
| CPEs | cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Rrrene
Rrrene html Sanitize Ex |
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| References |
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| Metrics |
cvssV4_0
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Status: PUBLISHED
Assigner: EEF
Published:
Updated: 2026-08-06T15:44:22.358Z
Reserved: 2026-07-31T13:23:00.355Z
Link: CVE-2026-68749
Updated: 2026-08-06T15:44:18.372Z
No data.
No data.
OpenCVE Enrichment
Updated: 2026-08-06T18:15:02Z