How severe is CVE-2021-35943?

CVE-2021-35943 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-2021-35943 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-35943?

CVE-2021-35943 affects Couchbase Couchbase Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-35943?

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-2021-35943 published?

CVE-2021-35943 was published on 2021-09-29 and last updated on 2026-06-17.

CVE-2021-35943

CVE-2021-35943 is a critical-severity vulnerability in Couchbase Couchbase Server 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-287.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (59th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Couchbase Couchbase Server
Published: 2021-09-29
Last modified: 2026-06-17

Description

Couchbase Server 6.5.x and 6.6.x through 6.6.2 has Incorrect Access Control. Externally managed users are not prevented from using an empty password, per RFC4513.

Frequently asked questions

What is CVE-2021-35943?: Couchbase Server 6.5.x and 6.6.x through 6.6.2 has Incorrect Access Control. Externally managed users are not prevented from using an empty password, per RFC4513.
How severe is CVE-2021-35943?: CVE-2021-35943 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-2021-35943 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-35943?: CVE-2021-35943 affects Couchbase Couchbase Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-35943?: 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-2021-35943 published?: CVE-2021-35943 was published on 2021-09-29 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:couchbase:couchbase_server:*:*:*:*:*:*:*:*

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