Skip to content
Noroxi
CVE-2019-5636· NVD / CVE Program· CNA rapid7

Beckhoff TwinCAT Discovery Service Denial of Service

Noroxi assessment

Priority: Monitor (action score 30/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 1.4% (FIRST EPSS); higher than 72.2% of all records.
  • 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.
  • According to the record, no fixed version is available yet.
  • Severity is disputed: the assigning authority (CNA) scores it 5.3, NVD 7.5.

Low priority for now. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

When a Beckhoff TwinCAT Runtime receives a malformed UDP packet, the ADS Discovery Service shuts down. Note that the TwinCAT devices are still performing as normal. This issue affects TwinCAT 2 version 2304 (and prior) and TwinCAT 3.1 version 4204.0 (and prior).

HighCVSS 7.5 · v3.1—No exploit No fix recorded
Published
Nov 21, 2019
Updated
Jun 16, 2026
EPSS
1.4% · 72th percentile

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 · 1.4%

CNA vs NVD score

NVD
7.5
CNA · rapid7
5.3
2.2 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • No fixed version yet

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2019-5636

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

Your free account also gets you

Running WordPress? Scan your site free with WP Lens

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Port scanning: 5 full scans a day (members only)
  • Uptime monitoring: 1 site, instant email when it goes down
  • Verify your domain: subdomains and takeover risk scanned every week
  • 10 scans an hour on the security tools (3 a day without an account), an API key and MCP
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for beckhoff records

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
beckhofftwincat

Affected versions

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

  • beckhoff twincat2.0
  • beckhoff twincat3.1

Versions reported by the vendor

Affected version ranges reported by the assigning authority (rapid7). Independent of NVD's CPE analysis and usually ahead of it.

  • Beckhoff TwinCAT 2

    • 2304 and later · up to and including 2304affected

  • Beckhoff TwinCAT 3.1

    • 4204.0 and later · up to and including 4204.0affected

Same product

beckhoff: all records

Other highest-scoring records for the same primary product.

  • CVE-2019-16871Beckhoff Embedded Windows PLCs through 3.1.4024.0, and Beckhoff Twincat on Windows Engineering stations, allow an attacker to achieve Remote
    41Plan
  • CVE-2017-16726Beckhoff TwinCAT supports communication over ADS.
    36Monitor
  • CVE-2011-3486Beckhoff TwinCAT 2.11.0.2004 and earlier allows remote attackers to cause a denial of service via a crafted request to UDP port 48899, which
    35Monitor
  • CVE-2018-7502Kernel drivers in Beckhoff TwinCAT 3.1 Build 4022.4, TwinCAT 2.11 R3 2259, and TwinCAT 3.1 lack proper validation of user-supplied pointer v
    31Monitor
  • CVE-2019-5637Beckhoff TwinCAT Profinet Driver Divide-by-Zero Denial of Service
    30Monitor
  • CVE-2017-16718Beckhoff TwinCAT 3 supports communication over ADS.
    23Monitor

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.

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-404 · Improper Resource Shutdown or Release

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.

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