How severe is CVE-2023-36521?

CVE-2023-36521 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2023-36521 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-36521?

CVE-2023-36521 primarily affects Siemens Simatic Mv540 H Firmware. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-36521?

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

When was CVE-2023-36521 published?

CVE-2023-36521 was published on 2023-07-11 and last updated on 2026-06-17.

CVE-2023-36521

CVE-2023-36521 is a high-severity vulnerability in Siemens Simatic Mv540 H Firmware with a CVSS 3.x base score of 8.6. 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-770.

Key facts

Severity: High (CVSS 3.x base score 8.6)
EPSS exploit prediction: 1% (41st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-770
Affected product: Siemens Simatic Mv540 H Firmware
Published: 2023-07-11
Last modified: 2026-06-17

Description

A vulnerability has been identified in SIMATIC MV540 H (All versions < V3.3.4), SIMATIC MV540 S (All versions < V3.3.4), SIMATIC MV550 H (All versions < V3.3.4), SIMATIC MV550 S (All versions < V3.3.4), SIMATIC MV560 U (All versions < V3.3.4), SIMATIC MV560 X (All versions < V3.3.4). The result synchronization server of the affected products contains a vulnerability that may lead to a denial of service condition. An attacker may cause a denial of service situation of all socket-based communication of the affected products if the result server is enabled.

Frequently asked questions

What is CVE-2023-36521?: A vulnerability has been identified in SIMATIC MV540 H (All versions < V3.3.4), SIMATIC MV540 S (All versions < V3.3.4), SIMATIC MV550 H (All versions < V3.3.4), SIMATIC MV550 S (All versions < V3.3.4), SIMATIC MV560 U (All versions < V3.3.4), SIMATIC MV560 X (All versions < V3.3.4). The result synchronization server of the affected products contains a vulnerability that may lead to a denial of service condition. An attacker may cause a denial of service situation of all socket-based communication of the affected products if the result server is enabled.
How severe is CVE-2023-36521?: CVE-2023-36521 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2023-36521 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-36521?: CVE-2023-36521 primarily affects Siemens Simatic Mv540 H Firmware. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-36521?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2023-36521 published?: CVE-2023-36521 was published on 2023-07-11 and last updated on 2026-06-17.

References

https://cert-portal.siemens.com/productcert/pdf/ssa-561322.pdf

Affected products (6)

cpe:2.3:o:siemens:simatic_mv540_h_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_mv540_s_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_mv550_h_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_mv550_s_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_mv560_u_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:simatic_mv560_x_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Siemens Simatic Mv540 H Firmware

CVE-2022-33137 — High (CVSS 8.0): A vulnerability has been identified in SIMATIC MV540 H (All versions < V3.3), SIMATIC MV540 S (All versions < V3.3),…
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CVE-2022-33138 — High (CVSS 7.5): A vulnerability has been identified in SIMATIC MV540 H (All versions < V3.3), SIMATIC MV540 S (All versions < V3.3),…

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