Apache PLC4X, Apache PLC4X: Pre-authentication resource exhaustion in the OPC UA driver and the Java SPI parser

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No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Memory Allocation with Excessive Size Value, Allocation of Resources Without Limits, and Uncontrolled Recursion in the Java implementation of Apache PLC4X (PLC4J) allow a malicious or impersonated device to exhaust the memory or stack of the client application, causing a denial of service. In the OPC UA driver these defects are reachable before authentication: the offending data is parsed while the secure channel and session are being established, before the server's identity has been bound to it. Configuring a trusted server therefore does not prevent exploitation by an attacker who can impersonate it. The individual defects are: - Length-prefixed byte strings are allocated at the size claimed on the wire before the length is checked against the data actually received (0.10.0 through 0.13.1). - Array fields in generated protocol parsers pre-allocate a list with the element count claimed on the wire, allowing a single count field to trigger a multi-gigabyte allocation. This parser is shared by all PLC4J drivers; the OPC UA driver is the verified pre-authentication path (0.10.0 through 0.13.1). - The OPC UA driver accumulates message chunks without enforcing the negotiated maximum chunk count and message size (0.12.0 through 0.13.1). - The OPC UA driver pre-allocates collections using element counts received from the server (0.10.0 through 0.13.1). - Recursive protocol types are parsed without a nesting-depth limit. The same defect in the Go implementation is covered by CVE-2026-102510 https://cveprocess.apache.org/cve5/CVE-2026-102510 . This issue affects Apache PLC4X: from 0.10.0 before 1.0.0. Users are recommended to upgrade to version 1.0.0, which fixes the issue.

Source published

30 Sep 2026 08:00:27 UTC

Source modified

30 Sep 2026 14:40:06 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 4.0 · 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N