How severe is CVE-2021-25668?

CVE-2021-25668 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-2021-25668 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-25668?

CVE-2021-25668 primarily affects Siemens Scalance X200-4p Irt Firmware. In total, 29 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-25668?

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-2021-25668 published?

CVE-2021-25668 was published on 2021-04-22 and last updated on 2026-06-17.

CVE-2021-25668

CVE-2021-25668 is a critical-severity vulnerability in Siemens Scalance X200-4p Irt Firmware 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-122.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (72nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-122
Affected product: Siemens Scalance X200-4p Irt Firmware
Published: 2021-04-22
Last modified: 2026-06-17

Description

A vulnerability has been identified in SCALANCE X200-4P IRT (All versions < 5.5.1), SCALANCE X201-3P IRT (All versions < 5.5.1), SCALANCE X201-3P IRT PRO (All versions < 5.5.1), SCALANCE X202-2 IRT (All versions < 5.5.1), SCALANCE X202-2P IRT (incl. SIPLUS NET variant) (All versions < 5.5.1), SCALANCE X202-2P IRT PRO (All versions < 5.5.1), SCALANCE X204 IRT (All versions < 5.5.1), SCALANCE X204 IRT PRO (All versions < 5.5.1), SCALANCE X204-2 (incl. SIPLUS NET variant) (All versions < V5.2.5), SCALANCE X204-2FM (All versions < V5.2.5), SCALANCE X204-2LD (incl. SIPLUS NET variant) (All versions < V5.2.5), SCALANCE X204-2LD TS (All versions < V5.2.5), SCALANCE X204-2TS (All versions < V5.2.5), SCALANCE X206-1 (All versions < V5.2.5), SCALANCE X206-1LD (All versions < V5.2.5), SCALANCE X208 (incl. SIPLUS NET variant) (All versions < V5.2.5), SCALANCE X208PRO (All versions < V5.2.5), SCALANCE X212-2 (incl. SIPLUS NET variant) (All versions < V5.2.5), SCALANCE X212-2LD (All versions < V5.2.5), SCALANCE X216 (All versions < V5.2.5), SCALANCE X224 (All versions < V5.2.5), SCALANCE XF201-3P IRT (All versions < 5.5.1), SCALANCE XF202-2P IRT (All versions < 5.5.1), SCALANCE XF204 (All versions < V5.2.5), SCALANCE XF204 IRT (All versions < 5.5.1), SCALANCE XF204-2 (incl. SIPLUS NET variant) (All versions < V5.2.5), SCALANCE XF204-2BA IRT (All versions < 5.5.1), SCALANCE XF206-1 (All versions < V5.2.5), SCALANCE XF208 (All versions < V5.2.5). Incorrect processing of POST requests in the webserver may result in write out of bounds in heap. An attacker might leverage this to cause denial-of-service on the device and potentially remotely execute code.

Frequently asked questions

What is CVE-2021-25668?: A vulnerability has been identified in SCALANCE X200-4P IRT (All versions < 5.5.1), SCALANCE X201-3P IRT (All versions < 5.5.1), SCALANCE X201-3P IRT PRO (All versions < 5.5.1), SCALANCE X202-2 IRT (All versions < 5.5.1), SCALANCE X202-2P IRT (incl. SIPLUS NET variant) (All versions < 5.5.1), SCALANCE X202-2P IRT PRO (All versions < 5.5.1), SCALANCE X204 IRT (All versions < 5.5.1), SCALANCE X204 IRT PRO (All versions < 5.5.1), SCALANCE X204-2 (incl. SIPLUS NET variant) (All versions < V5.2.5), SCALANCE X204-2FM (All versions < V5.2.5), SCALANCE X204-2LD (incl. SIPLUS NET variant) (All versions < V5.2.5), SCALANCE X204-2LD TS (All versions < V5.2.5), SCALANCE X204-2TS (All versions < V5.2.5), SCALANCE X206-1 (All versions < V5.2.5), SCALANCE X206-1LD (All versions < V5.2.5), SCALANCE X208 (incl. SIPLUS NET variant) (All versions < V5.2.5), SCALANCE X208PRO (All versions < V5.2.5), SCALANCE X212-2 (incl. SIPLUS NET variant) (All versions < V5.2.5), SCALANCE X212-2LD (All versions < V5.2.5), SCALANCE X216 (All versions < V5.2.5), SCALANCE X224 (All versions < V5.2.5), SCALANCE XF201-3P IRT (All versions < 5.5.1), SCALANCE XF202-2P IRT (All versions < 5.5.1), SCALANCE XF204 (All versions < V5.2.5), SCALANCE XF204 IRT (All versions < 5.5.1), SCALANCE XF204-2 (incl. SIPLUS NET variant) (All versions < V5.2.5), SCALANCE XF204-2BA IRT (All versions < 5.5.1), SCALANCE XF206-1 (All versions < V5.2.5), SCALANCE XF208 (All versions < V5.2.5). Incorrect processing of POST requests in the webserver may result in write out of bounds in heap. An attacker might leverage this to cause denial-of-service on the device and potentially remotely execute code.
How severe is CVE-2021-25668?: CVE-2021-25668 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-2021-25668 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-25668?: CVE-2021-25668 primarily affects Siemens Scalance X200-4p Irt Firmware. In total, 29 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-25668?: 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-2021-25668 published?: CVE-2021-25668 was published on 2021-04-22 and last updated on 2026-06-17.

References

https://cert-portal.siemens.com/productcert/pdf/ssa-187092.pdf

Affected products (29)

cpe:2.3:o:siemens:scalance_x200-4p_irt_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x201-3p_irt_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x201-3p_irt_pro_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x202-2_irt_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x202-2p_irt_pro_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x204_irt_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x204_irt_pro_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x204-2_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x204-2fm_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x204-2ld_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x204-2ld_ts_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x204-2ts_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x206-1_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x206-1ld_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x208_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x208pro_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x212-2_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x212-2ld_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x216_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x224_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_xf201-3p_irt_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_xf202-2p_irt_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_xf204_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_xf204_irt_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_xf204-2_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_xf204-2ba_irt_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_xf206-1_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_xf208_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:siemens:scalance_x202-2p_irt_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Siemens Scalance X200-4p Irt Firmware

CVE-2021-25669 — Critical (CVSS 9.8): A vulnerability has been identified in SCALANCE X200-4P IRT (All versions < 5.5.1), SCALANCE X201-3P IRT (All versions…
CVE-2022-26649 — Critical (CVSS 9.6): A vulnerability has been identified in SCALANCE X200-4P IRT (All versions < V5.5.2), SCALANCE X201-3P IRT (All versions…
CVE-2022-26647 — High (CVSS 8.8): A vulnerability has been identified in SCALANCE X200-4P IRT (All versions < V5.5.2), SCALANCE X201-3P IRT (All versions…
CVE-2022-26648 — High (CVSS 8.2): A vulnerability has been identified in SCALANCE X200-4P IRT (All versions < V5.5.2), SCALANCE X201-3P IRT (All versions…
CVE-2023-29054 — Medium (CVSS 6.7): A vulnerability has been identified in SCALANCE X200-4P IRT (All versions < V5.5.2), SCALANCE X201-3P IRT (All versions…
CVE-2022-40631 — Medium (CVSS 6.1): A vulnerability has been identified in SCALANCE X200-4P IRT (All versions < V5.5.0), SCALANCE X201-3P IRT (All versions…

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