CPU exhaustion via quadratic sibling re-flattening
Published Aug 6, 2026 · Updated Aug 6, 2026
Algorithmic complexity in html_sanitize_ex 0.3.1 through 1.4.4 and 1.5.0-rc.0 through 1.5.2 allows remote attackers to exhaust resources. The HtmlSanitizeEx.Traverser.traverse/2 list clause recursively processes each tail, then flattens the already flattened result, repeatedly copying and walking the remaining siblings. Every public sanitizer entry point reaches the clause without a special scrubber or disallowed tags, so a flat sibling sequence can occupy a scheduler and consume server CPU and memory.
Summary
What happened
Algorithmic complexity in html_sanitize_ex 0.3.1 through 1.4.4 and 1.5.0-rc.0 through 1.5.2 allows remote attackers to exhaust resources. The HtmlSanitizeEx.Traverser.traverse/2 list clause recursively processes each tail, then flattens the already flattened result, repeatedly copying and walking the remaining siblings. Every public sanitizer entry point reaches the clause without a special scrubber or disallowed tags, so a flat sibling sequence can occupy a scheduler and consume server CPU and memory.
The record
- CVE
- CVE-2026-68750
- Published
- Aug 6, 2026
- Updated
- Aug 6, 2026
- Vendor
- René Föhring
- Product
- html_sanitize_ex
- Classifications
- CWE-407, CAPEC-130, T1499.003
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 6, 2026CVE publishedPublication date reported by the CVE source.
- Aug 6, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0.3.1 <1.5.3
- Affected versionversion=69ea11d61525c470b39b6860d024770d5573ff1f <9f5ccedbed230930813f992a1e6906fcf485981e
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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