Vulnerability Description
Inefficient Algorithmic Complexity vulnerability in the traversal engine in rrrene html_sanitize_ex allows an unauthenticated remote attacker to exhaust server CPU and memory via a flat run of sibling elements in sanitized HTML. The list clause of HtmlSanitizeEx.Traverser.traverse/2 recurses on the tail of a sibling list and then evaluates List.flatten([head] ++ tail) over the already flattened result, so every one of n siblings copies and re-walks the entire remaining tail. The flattening is only needed for the rare case where scrub returns several replacement nodes for one node, but the cost is paid across the whole tail at every step, making traversal quadratic in sibling count. The traverser sits on every public entry point, so no particular scrubber or configuration is required and the payload needs only allowed tags. A 160 KB body of 20,000 sibling elements occupies a scheduler for roughly 1.7 seconds, and the cost grows faster than the body does. This issue affects html_sanitize_ex: from 0.3.1 before 1.5.3.
Related Weaknesses (CWE)
References
- https://cna.erlef.org/cves/CVE-2026-68750.html
- https://github.com/rrrene/html_sanitize_ex/commit/9f5ccedbed230930813f992a1e6906
- https://github.com/rrrene/html_sanitize_ex/security/advisories/GHSA-463q-p2fr-mh
- https://osv.dev/vulnerability/EEF-CVE-2026-68750
FAQ
What is CVE-2026-68750?
CVE-2026-68750 is a documented vulnerability. Inefficient Algorithmic Complexity vulnerability in the traversal engine in rrrene html_sanitize_ex allows an unauthenticated remote attacker to exhaust server CPU and memory via a flat run of sibling...
How severe is CVE-2026-68750?
CVSS scoring is not yet available for CVE-2026-68750. Check NVD for updates.
Is there a patch for CVE-2026-68750?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.