CVE-2026-33592

FindServers Memory Exhaustion in open62541

State: Published
Severity: 7.5 High
Published: Jul 2, 2026
Updated: Jul 2, 2026
Reserved: Mar 23, 2026

Description

An unauthenticated remote attacker can exhaust server memory via the FindServers Discovery Service in open62541. The serverUris field of FindServersRequest is not validated for length or array size. An attacker can declare an arbitrarily large string (up to ~3.9 GB) delivered across intermediate chunks without ever sending the final chunk. The server buffers all chunks in RAM indefinitely until the SecureChannel times out. The attack is pre-session and bypasses all encryption configuration. The issue affects open62541: from 1.4.0 through 1.4.16, from 1.5.0 through 1.5.4, master.

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	ENISA

Weaknesses

CWE-770 Allocation of resources without limits or throttling
CWE-789 Memory allocation with excessive size value

Affected Products

Product	Versions
open62541open62541 project / o6 Automation GmbH	1.4.0 through 1.4.16Affected 1.5.0 through 1.5.4Affected masterAffected

References

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