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NVD / CVE Program· CNA talos

CVE-2020-13556: An out-of-bounds write vulnerability exists in the Ethernet/IP server functionality of EIP Stack Group OpENer 2.3 and development commit…

CriticalCVSS 9.8 · v3.1—No exploit No fix recorded

Noroxi assessment

Priority: Plan (action score 40/100)

  • 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: 4.7% (FIRST EPSS); higher than 91.9% 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.

Add it to your regular patch cycle. 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

Primary sources: NVD · CVE.org · FIRST EPSS

An out-of-bounds write vulnerability exists in the Ethernet/IP server functionality of EIP Stack Group OpENer 2.3 and development commit 8c73bf3. A specially crafted series of network requests can lead to remote code execution. An attacker can send a sequence of requests to trigger this vulnerability.

Published
Dec 11, 2020
Updated
Jun 16, 2026
EPSS
4.7% · 91th percentile

Report tools

JSON

Action score

40

Plan

Add it to your regular patch cycle.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 4.7%

CNA vs NVD score

NVD
9.8
CNA · talos
9.8
agree

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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-2020-13556

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

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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.

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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
opener projectopener

Versions reported by the vendor

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

  • n/a EIP Stack Group

    • EIP Stack Group OpENer 2.3, EIP Stack Group OpENer development commit 8c73bf3affected

Affected versions

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

  • opener project opener2.3

Same product

opener project: all records

Other highest-scoring records for the same primary product.

  • CVE-2022-43605An out-of-bounds write vulnerability exists in the SetAttributeList attribute_count_request functionality of EIP Stack Group OpENer…
    43Plan
  • CVE-2022-43604An out-of-bounds write vulnerability exists in the GetAttributeList attribute_count_request functionality of EIP Stack Group OpENer…
    43Plan
  • CVE-2021-21777An information disclosure vulnerability exists in the Ethernet/IP UDP handler functionality of EIP Stack Group OpENer 2.3 and development…
    41Plan

Published before and after this one in the same product

  • ← EarlierCVE-2020-13530Dec 11, 2020 · A denial-of-service vulnerability exists in the Ethernet/IP server functionality of the EIP Stack Group OpENer 2.3 and development commit…
    31Monitor
  • Later →CVE-2021-27478May 12, 2022 · EIPStackGroup OpENer Ethernet/IP Incorrect Conversion between Numeric Types
    30Monitor
  • Later →CVE-2021-27482May 12, 2022 · EIPStackGroup OpENer Ethernet/IP Out-of-bounds Read
    30Monitor

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.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

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

Weakness class (CWE)

CWE-787 · Out-of-bounds Write

CVSS vector

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

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