How severe is CVE-2021-33900?

CVE-2021-33900 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 high, integrity none, and availability none.

Is CVE-2021-33900 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-33900?

CVE-2021-33900 primarily affects Apache Directory Studio. In total, 17 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-33900?

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-2021-33900 published?

CVE-2021-33900 was published on 2021-07-26 and last updated on 2026-06-17.

CVE-2021-33900

CVE-2021-33900 is a high-severity vulnerability in Apache Directory Studio 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-319.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (52nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-319
Affected product: Apache Directory Studio
Published: 2021-07-26
Last modified: 2026-06-17

Description

While investigating DIRSTUDIO-1219 it was noticed that configured StartTLS encryption was not applied when any SASL authentication mechanism (DIGEST-MD5, GSSAPI) was used. While investigating DIRSTUDIO-1220 it was noticed that any configured SASL confidentiality layer was not applied. This issue affects Apache Directory Studio version 2.0.0.v20210213-M16 and prior versions.

Frequently asked questions

What is CVE-2021-33900?: While investigating DIRSTUDIO-1219 it was noticed that configured StartTLS encryption was not applied when any SASL authentication mechanism (DIGEST-MD5, GSSAPI) was used. While investigating DIRSTUDIO-1220 it was noticed that any configured SASL confidentiality layer was not applied. This issue affects Apache Directory Studio version 2.0.0.v20210213-M16 and prior versions.
How severe is CVE-2021-33900?: CVE-2021-33900 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 high, integrity none, and availability none.
Is CVE-2021-33900 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-33900?: CVE-2021-33900 primarily affects Apache Directory Studio. In total, 17 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-33900?: 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-2021-33900 published?: CVE-2021-33900 was published on 2021-07-26 and last updated on 2026-06-17.

References

https://lists.apache.org/thread.html/rb1dbcc43a5b406e45d335343a1704f4233de613140a01929d102fdc9%40%3Cusers.directory.apache.org%3E

Affected products (17)

cpe:2.3:a:apache:directory_studio:*:*:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone1:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone10:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone11:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone12:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone13:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone14:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone15:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone16:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone2:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone3:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone4:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone5:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone6:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone7:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone8:*:*:*:*:*:*
cpe:2.3:a:apache:directory_studio:2.0.0:milestone9:*:*:*:*:*:*

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