CVE-2026-68750 (GCVE-0-2026-68750)

Vulnerability from cvelistv5 – Published: 2026-08-06 14:50 – Updated: 2026-08-06 15:41
VLAI
Title
Quadratic sibling re-flattening in the html_sanitize_ex traversal engine allows CPU-exhaustion denial of service
Summary
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.
Severity
8.2 (High)
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
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-407 - Inefficient Algorithmic Complexity
Assigner
EEF
References
Impacted products
Vendor Product Version
rrrene html_sanitize_ex Affected: 0.3.1 , < 1.5.3 (semver)
    cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*
 Create a notification for this product.
rrrene html_sanitize_ex Affected: 69ea11d61525c470b39b6860d024770d5573ff1f , < 9f5ccedbed230930813f992a1e6906fcf485981e (git)
    cpe:2.3:a:rrrene:html_sanitize_ex:*:*:*:*:*:*:*:*
 Create a notification for this product.
Credits
Peter Ullrich Jonatan Männchen / EEF René Föhring
Show details on NVD website
To clipboard 

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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.