How severe is CVE-2020-13556?

CVE-2020-13556 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-2020-13556 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (90th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-13556?

CVE-2020-13556 affects Opener Project Opener. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-13556?

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-2020-13556 published?

CVE-2020-13556 was published on 2020-12-11 and last updated on 2026-06-17.

CVE-2020-13556

CVE-2020-13556 is a critical-severity vulnerability in Opener Project Opener 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-787.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 5% (90th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Opener Project Opener
Published: 2020-12-11
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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 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.
How severe is CVE-2020-13556?: CVE-2020-13556 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-2020-13556 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 5% (90th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-13556?: CVE-2020-13556 affects Opener Project Opener. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-13556?: 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-2020-13556 published?: CVE-2020-13556 was published on 2020-12-11 and last updated on 2026-06-17.

References

https://talosintelligence.com/vulnerability_reports/TALOS-2020-1170

Affected products (1)

cpe:2.3:a:opener_project:opener:2.3:*:*:*:*:*:*:*

More vulnerabilities in Opener Project Opener

CVE-2022-43605 — Critical (CVSS 10.0): An out-of-bounds write vulnerability exists in the SetAttributeList attribute_count_request functionality of EIP Stack…
CVE-2022-43604 — Critical (CVSS 10.0): An out-of-bounds write vulnerability exists in the GetAttributeList attribute_count_request functionality of EIP Stack…
CVE-2021-21777 — Critical (CVSS 10.0): An information disclosure vulnerability exists in the Ethernet/IP UDP handler functionality of EIP Stack Group OpENer…
CVE-2021-27478 — High (CVSS 8.2): A specifically crafted packet sent by an attacker to EIPStackGroup OpENer EtherNet/IP commits and versions prior to Feb…
CVE-2022-32434 — High (CVSS 7.8): EIPStackGroup OpENer v2.3.0 was discovered to contain a stack overflow via /bin/posix/src/ports/POSIX/OpENer+0x56073d.
CVE-2022-43606 — High (CVSS 7.5): A use-of-uninitialized-pointer vulnerability exists in the Forward Open connection_management_entry functionality of…

All CVEs affecting Opener Project Opener →

Other CWE-787 (Out-of-bounds Write) vulnerabilities

CVE-2026-42369 — Critical (CVSS 10.0): GV-VMS V20 is a Video Monitoring Software used to gather the feeds of many surveillance cameras and manage other…
CVE-2026-4746 — Critical (CVSS 10.0): Out-of-bounds Write vulnerability in timeplus-io proton (base/poco/Foundation/src‎ modules). This vulnerability is…
CVE-2025-43300 — Critical (CVSS 10.0): An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 15.8.5 and iPadOS…
CVE-2025-24201 — Critical (CVSS 10.0): An out-of-bounds write issue was addressed with improved checks to prevent unauthorized actions. This issue is fixed in…
CVE-2024-42479 — Critical (CVSS 10.0): llama.cpp provides LLM inference in C/C++. The unsafe `data` pointer member in the `rpc_tensor` structure can cause…
CVE-2024-39791 — Critical (CVSS 10.0): Stack-based buffer overflow vulnerabilities affecting Vonets industrial wifi bridge relays and wifi bridge…

Browse all CWE-787 (Out-of-bounds Write) vulnerabilities →