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CVE-2021-25660· NVD / CVE Program· CNA siemens

A vulnerability has been identified in SIMATIC HMI Comfort Outdoor Panels V15 7\" & 15\" (incl.

A vulnerability has been identified in SIMATIC HMI Comfort Outdoor Panels V15 7\" & 15\" (incl. SIPLUS variants) (All versions < V15.1 Update 6), SIMATIC HMI Comfort Outdoor Panels V16 7\" & 15\" (incl. SIPLUS variants) (All versions < V16 Update 4), SIMATIC HMI Comfort Panels V15 4\" - 22\" (incl. SIPLUS variants) (All versions < V15.1 Update 6), SIMATIC HMI Comfort Panels V16 4\" - 22\" (incl. SIPLUS variants) (All versions < V16 Update 4), SIMATIC HMI KTP Mobile Panels V15 KTP400F, KTP700, KTP700F, KTP900 and KTP900F (All versions < V15.1 Update 6), SIMATIC HMI KTP Mobile Panels V16 KTP400F, KTP700, KTP700F, KTP900 and KTP900F (All versions < V16 Update 4), SIMATIC WinCC Runtime Advanced V15 (All versions < V15.1 Update 6), SIMATIC WinCC Runtime Advanced V16 (All versions < V16 Update 4). SmartVNC has an out-of-bounds memory access vulnerability that could be triggered on the server side when sending data from the client, which could result in a Denial-of-Service condition.

HighCVSS 7.5 · v3.1—No exploit No fix recorded
Published
May 12, 2021
Updated
Jun 16, 2026
EPSS
1.0% · 61th percentile
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Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 1.0%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

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Affected systems

VendorProduct
siemenssimatic hmi comfort outdoor panels 7\" firmware
siemenssimatic hmi comfort outdoor panels 7\"
siemenssimatic hmi comfort outdoor panels 15\" firmware
siemenssimatic hmi comfort outdoor panels 15\"
siemenssimatic hmi comfort panels 4\" firmware
siemenssimatic hmi comfort panels 4\"
siemenssimatic hmi comfort panels 22\" firmware
siemenssimatic hmi comfort panels 22\"
siemenssimatic hmi ktp mobile panels ktp400f firmware
siemenssimatic hmi ktp mobile panels ktp400f
siemenssimatic hmi ktp mobile panels ktp700 firmware
siemenssimatic hmi ktp mobile panels ktp700

and 7 more

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • siemens simatic hmi comfort outdoor panels 15" firmwarebefore 15.1
  • siemens simatic hmi comfort outdoor panels 15" firmwarebefore 16
  • siemens simatic hmi comfort outdoor panels 15" firmware15.1
  • siemens simatic hmi comfort outdoor panels 15" firmware16
  • siemens simatic hmi comfort outdoor panels 7" firmwarebefore 16
  • siemens simatic hmi comfort outdoor panels 7" firmwarebefore 15.1
  • siemens simatic hmi comfort outdoor panels 7" firmware15.1
  • siemens simatic hmi comfort outdoor panels 7" firmware16
  • siemens simatic hmi comfort panels 22" firmwarebefore 16
  • siemens simatic hmi comfort panels 22" firmwarebefore 15.1
  • siemens simatic hmi comfort panels 22" firmware15.1
  • siemens simatic hmi comfort panels 22" firmware16
  • siemens simatic hmi comfort panels 4" firmwarebefore 16
  • siemens simatic hmi comfort panels 4" firmwarebefore 15.1
  • siemens simatic hmi comfort panels 4" firmware15.1
  • siemens simatic hmi comfort panels 4" firmware16
  • siemens simatic hmi ktp mobile panels ktp400f firmwarebefore 16
  • siemens simatic hmi ktp mobile panels ktp400f firmwarebefore 15.1
  • siemens simatic hmi ktp mobile panels ktp400f firmware15.1
  • siemens simatic hmi ktp mobile panels ktp400f firmware16

Versions reported by the vendor

Affected version ranges reported by the assigning authority (siemens). Independent of NVD's CPE analysis and usually ahead of it.

  • Siemens SIMATIC HMI Comfort Outdoor Panels V15 7\" & 15\" (incl. SIPLUS variants)

    • All versions < V15.1 Update 6affected

  • Siemens SIMATIC HMI Comfort Outdoor Panels V16 7\" & 15\" (incl. SIPLUS variants)

    • All versions < V16 Update 4affected

  • Siemens SIMATIC HMI Comfort Panels V15 4\" - 22\" (incl. SIPLUS variants)

    • All versions < V15.1 Update 6affected

  • Siemens SIMATIC HMI Comfort Panels V16 4\" - 22\" (incl. SIPLUS variants)

    • All versions < V16 Update 4affected

  • Siemens SIMATIC HMI KTP Mobile Panels V15 KTP400F, KTP700, KTP700F, KTP900 and KTP900F

    • All versions < V15.1 Update 6affected

  • Siemens SIMATIC HMI KTP Mobile Panels V16 KTP400F, KTP700, KTP700F, KTP900 and KTP900F

    • All versions < V16 Update 4affected

  • Siemens SIMATIC WinCC Runtime Advanced V15

    • All versions < V15.1 Update 6affected

  • Siemens SIMATIC WinCC Runtime Advanced V16

    • All versions < V16 Update 4affected

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-788 · Access of Memory Location After End of Buffer

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records