CVE-2026-104712: Apache Struts: Disproportionate response size when rendering BigDecimal request parameters

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-05 · updated 2026-10-08
Weakness: CWE-405

Description

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.

Affected products

Apache Struts: from 2.5.14 through 2.5.33; from 6.0.0 before 6.12.0; from 7.0.0 before 7.4.0 — fixed in 6.12.0, 7.4.0

How to fix

Upgrade to a fixed version: Apache Struts 6.12.0, 7.4.0. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-104712 or the next vulnerability affects your stack