CVE-2026-33592

HIGH 7.5

FindServers Memory Exhaustion in open62541

CVSS Score

7.5

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-770 CWE-789
Vendor	open62541 project / o6 automation gmbh
Product	open62541
Published	Jul 2, 2026
Last Updated	Jul 2, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Affected Versions

open62541 project / o6 Automation GmbH / open62541

1.4.0 ≤ 1.4.16 1.5.0 ≤ 1.5.4 master

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/open62541/open62541/pull/8142 github.com: https://github.com/open62541/open62541/pull/8142/changes/d253818d6c5e870e1db0e360b18138c8bdc809ae github.com: https://github.com/open62541/open62541

Credits

Lorenzo Cannella from Fondazione Ugo Bordoni (FUB)