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CVE-2021-25662

23
FAUCET Score

CVE-2021-25662 is a denial-of-service vulnerability affecting various Siemens SIMATIC HMI Comfort Panels, KTP Mobile Panels, and WinCC Runtime Advanced versions. The flaw stems from the SmartVNC client's improper exception handling when program execution is modified after a server packet is sent. With a CVSS score of 7.5 (High), this vulnerability can be exploited remotely with low attack complexity, leading to a complete loss of availability for affected systems. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 16CPE matchmatch criteria
cpe:2.3:a:siemens:simatic_wincc_runtime_advanced:*:*:*:*:*:*:*:*
16CPE matchmatch criteria
cpe:2.3:a:siemens:simatic_wincc_runtime_advanced:16:-:*:*:*:*:*:*
16CPE matchmatch criteria
cpe:2.3:a:siemens:simatic_wincc_runtime_advanced:16:update1:*:*:*:*:*:*
16CPE matchmatch criteria
cpe:2.3:a:siemens:simatic_wincc_runtime_advanced:16:update2:*:*:*:*:*:*
16CPE matchmatch criteria
cpe:2.3:a:siemens:simatic_wincc_runtime_advanced:16:update3:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

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 Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.64%
Probability of exploitation in next 30 days
EPSS Percentile
73.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0164 is in the 56th percentile among its peer group of 51,553 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

cert-portal.siemens.com / productcert/pdf/ssa-538778.pdf
Vendor Advisory
us-cert.cisa.gov / ics/advisories/icsa-21-131-12
Third Party AdvisoryUS Government Resource