How severe is CVE-2021-3689?

CVE-2021-3689 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 high, and availability none.

Is CVE-2021-3689 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3689?

CVE-2021-3689 affects Yiiframework Yii. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-3689?

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-2021-3689 published?

CVE-2021-3689 was published on 2021-08-10 and last updated on 2026-06-17.

CVE-2021-3689

CVE-2021-3689 is a high-severity vulnerability in Yiiframework Yii 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-330.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (77th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-330
Affected product: Yiiframework Yii
Published: 2021-08-10
Last modified: 2026-06-17

Description

yii2 is vulnerable to Use of Predictable Algorithm in Random Number Generator

Frequently asked questions

What is CVE-2021-3689?: yii2 is vulnerable to Use of Predictable Algorithm in Random Number Generator
How severe is CVE-2021-3689?: CVE-2021-3689 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 high, and availability none.
Is CVE-2021-3689 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (77th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3689?: CVE-2021-3689 affects Yiiframework Yii. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-3689?: 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-2021-3689 published?: CVE-2021-3689 was published on 2021-08-10 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:yiiframework:yii:*:*:*:*:*:*:*:*

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