How severe is CVE-2021-36764?

CVE-2021-36764 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-36764 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-36764?

CVE-2021-36764 affects Codesys Gateway. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-36764?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-36764 published?

CVE-2021-36764 was published on 2021-08-04 and last updated on 2026-06-17.

CVE-2021-36764

CVE-2021-36764 is a high-severity vulnerability in Codesys Gateway with a CVSS 3.x base score of 7.5. 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-476.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (58th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-476
Affected product: Codesys Gateway
Published: 2021-08-04
Last modified: 2026-06-17

Description

In CODESYS Gateway V3 before 3.5.17.10, there is a NULL Pointer Dereference. Crafted communication requests may cause a Null pointer dereference in the affected CODESYS products and may result in a denial-of-service condition.

Frequently asked questions

What is CVE-2021-36764?: In CODESYS Gateway V3 before 3.5.17.10, there is a NULL Pointer Dereference. Crafted communication requests may cause a Null pointer dereference in the affected CODESYS products and may result in a denial-of-service condition.
How severe is CVE-2021-36764?: CVE-2021-36764 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-36764 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (58th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-36764?: CVE-2021-36764 affects Codesys Gateway. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-36764?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-36764 published?: CVE-2021-36764 was published on 2021-08-04 and last updated on 2026-06-17.

References

https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16804&token=d8c89c887979b22fdfc9fd5c3aa3804bbb1ddbff&download=

Affected products (1)

cpe:2.3:a:codesys:gateway:*:*:*:*:*:*:*:*

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Other CWE-476 (NULL Pointer Dereference) vulnerabilities

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CVE-2020-14500 — Critical (CVSS 10.0): Secomea GateManager all versions prior to 9.2c, An attacker can send a negative value and overwrite arbitrary data.
CVE-2010-2495 — Critical (CVSS 10.0): The pppol2tp_xmit function in drivers/net/pppol2tp.c in the L2TP implementation in the Linux kernel before 2.6.34 does…
CVE-2026-46195 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: smb: client: validate dacloffset before building…
CVE-2026-31657 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: batman-adv: hold claim backbone gateways by…
CVE-2026-31436 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: dmaengine: idxd: fix possible wrong descriptor…

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