Apache Struts: Disproportionate response size when rendering BigDecimal request parameters

Asymmetric resource consumption (amplification) vulnerability in Apache Struts. When a request parameter is bound to an arbitrary-precision decimal (java.math.BigDecimal) property that is then rendered through the Struts tag library, the framework can produce a response many orders of magnitude larger than the request, allowing an unauthenticated remote attacker to exhaust server CPU and outbound network capacity with sustained low-volume traffic. Applications that do not bind request parameters to BigDecimal properties, or never render such a property through the Struts tag library, are not affected. This issue affects Apache Struts: from 2.5.14 through 2.5.33, from 6.0.0 through 6.11.0, from 7.0.0 through 7.3.0. Users are recommended to upgrade to version 6.12.0 or 7.4.0, which fixes the issue.

Source published

5 Oct 2026 18:35:41 UTC

Source modified

6 Oct 2026 14:10:31 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

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