WAGO I/O-Check Service prone to Out-of-bounds Write

published 2022-11-09 3 y ago modified 2026-06-17 4 mo ago also EUVD-2021-21219

cvss: 9.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 1.0%; EPSS 1.0% chance of exploitation in 30 days, percentile 62%
public exploits: 0; none known

In WAGO I/O-Check Service in multiple products an attacker can send a specially crafted packet containing OS commands to crash the diagnostic tool and write memory.

Patch / fix

fixed in 20

wago 750-8100_firmware 18
wago 750-8101_firmware 18
wago 750-8101/025-000_firmware 18
wago 750-8102_firmware 18
wago 750-8102/025-000_firmware 18
wago 750-8202_firmware 18
wago 750-8202/000-011_firmware 18
wago 750-8202/000-012_firmware 18
wago 750-8202/000-022_firmware 18
wago 750-8202/025-000_firmware 18
wago 750-8202/025-001_firmware 18
wago 750-8202/025-002_firmware 18
wago 750-8202/040-000_firmware 18
wago 750-8202/040-001_firmware 18
wago 752-8303/8000-002_firmware 18
wago 762-4101_firmware 18
wago 762-4102_firmware 18
wago 762-4103_firmware 18
wago 762-4104_firmware 18
wago 762-4201/8000-001_firmware 18

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 18 mo ago (2025-05-01)

Exploit prediction

0.97% chance of exploitation in the next 30 days, higher than 62% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

WAGO 750-81xx/xxx-xxxFW
WAGO 750-82xx/xxx-xxx
WAGO 752-8303/8000-0002
WAGO 762-4xxx
WAGO 762-5xxx
WAGO 762-6xxx

Classification

Weakness

CWE-787 Out-of-bounds Write

References

cert.vde.com /en/advisories/VDE-2020-036/
third-party-advisory

Sources

CVE List CVE-2021-34569
NVD CVE-2021-34569

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary