How severe is CVE-2021-26788?

CVE-2021-26788 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-2021-26788 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (65th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-26788?

CVE-2021-26788 affects Oryx-embedded Cyclonetcp. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-26788?

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-2021-26788 published?

CVE-2021-26788 was published on 2021-03-08 and last updated on 2026-06-17.

CVE-2021-26788

CVE-2021-26788 is a high-severity vulnerability in Oryx-embedded Cyclonetcp 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-20.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (65th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Oryx-embedded Cyclonetcp
Published: 2021-03-08
Last modified: 2026-06-17

Description

Oryx Embedded CycloneTCP 1.7.6 to 2.0.0, fixed in 2.0.2, is affected by incorrect input validation, which may cause a denial of service (DoS). To exploit the vulnerability, an attacker needs to have TCP connectivity to the target system. Receiving a maliciously crafted TCP packet from an unauthenticated endpoint is sufficient to trigger the bug.

Frequently asked questions

What is CVE-2021-26788?: Oryx Embedded CycloneTCP 1.7.6 to 2.0.0, fixed in 2.0.2, is affected by incorrect input validation, which may cause a denial of service (DoS). To exploit the vulnerability, an attacker needs to have TCP connectivity to the target system. Receiving a maliciously crafted TCP packet from an unauthenticated endpoint is sufficient to trigger the bug.
How severe is CVE-2021-26788?: CVE-2021-26788 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-2021-26788 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (65th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-26788?: CVE-2021-26788 affects Oryx-embedded Cyclonetcp. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-26788?: 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-2021-26788 published?: CVE-2021-26788 was published on 2021-03-08 and last updated on 2026-06-17.

References

https://github.com/Oryx-Embedded/CycloneTCP/commit/de5336016edbe1e90327d0ed1cba5c4e49114366?branch=de5336016edbe1e90327d0ed1cba5c4e49114366&diff=split

Affected products (1)

cpe:2.3:a:oryx-embedded:cyclonetcp:*:*:*:*:*:*:*:*

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