rrrene html_sanitize_ex up to 1.5.2 Traversal Engine HtmlSanitizeEx.Traverser.traverse allocation of resources

Summaryinfo

A vulnerability marked as problematic has been reported in rrrene html_sanitize_ex up to 1.5.2. Affected is the function HtmlSanitizeEx.Traverser.traverse of the component Traversal Engine. Performing a manipulation results in allocation of resources. This vulnerability is cataloged as CVE-2026-68750. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as problematic has been found in rrrene html_sanitize_ex up to 1.5.2. This affects the function HtmlSanitizeEx.Traverser.traverse of the component Traversal Engine. The manipulation with an unknown input leads to a allocation of resources vulnerability. CWE is classifying the issue as CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. This is going to have an impact on availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-68750 since 07/31/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

Upgrading to version 1.5.3 eliminates this vulnerability.

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Productinfo

Vendor

• rrrene

Name

• html_sanitize_ex

Version

• 1.5.0
• 1.5.1
• 1.5.2

Website

• Product: https://github.com/rrrene/html_sanitize_ex/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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