How severe is CVE-2020-6994?

CVE-2020-6994 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-6994 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-6994?

CVE-2020-6994 primarily affects Belden Hirschmann Hios. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-6994?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2020-6994 published?

CVE-2020-6994 was published on 2020-04-03 and last updated on 2026-06-17.

CVE-2020-6994

CVE-2020-6994 is a critical-severity vulnerability in Belden Hirschmann Hios with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-120.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (73rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Belden Hirschmann Hios
Published: 2020-04-03
Last modified: 2026-06-17

Description

A buffer overflow vulnerability was found in some devices of Hirschmann Automation and Control HiOS and HiSecOS. The vulnerability is due to improper parsing of URL arguments. An attacker could exploit this vulnerability by specially crafting HTTP requests to overflow an internal buffer. The following devices using HiOS Version 07.0.02 and lower are affected: RSP, RSPE, RSPS, RSPL, MSP, EES, EES, EESX, GRS, OS, RED. The following devices using HiSecOS Version 03.2.00 and lower are affected: EAGLE20/30.

Frequently asked questions

What is CVE-2020-6994?: A buffer overflow vulnerability was found in some devices of Hirschmann Automation and Control HiOS and HiSecOS. The vulnerability is due to improper parsing of URL arguments. An attacker could exploit this vulnerability by specially crafting HTTP requests to overflow an internal buffer. The following devices using HiOS Version 07.0.02 and lower are affected: RSP, RSPE, RSPS, RSPL, MSP, EES, EES, EESX, GRS, OS, RED. The following devices using HiSecOS Version 03.2.00 and lower are affected: EAGLE20/30.
How severe is CVE-2020-6994?: CVE-2020-6994 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-6994 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (73rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-6994?: CVE-2020-6994 primarily affects Belden Hirschmann Hios. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-6994?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2020-6994 published?: CVE-2020-6994 was published on 2020-04-03 and last updated on 2026-06-17.

References

https://www.us-cert.gov/ics/advisories/icsa-20-091-01

Affected products (2)

cpe:2.3:o:belden:hirschmann_hios:*:*:*:*:*:*:*:*
cpe:2.3:o:belden:hirschmann_hisecos:*:*:*:*:*:*:*:*

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