How severe is CVE-2021-20839?

CVE-2021-20839 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-20839 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20839?

CVE-2021-20839 primarily affects Antennahouse Office Server Document Converter. In total, 23 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-20839?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-20839 published?

CVE-2021-20839 was published on 2021-11-01 and last updated on 2026-06-17.

CVE-2021-20839

CVE-2021-20839 is a medium-severity vulnerability in Antennahouse Office Server Document Converter with a CVSS 3.x base score of 6.5. 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-611.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.3
EPSS exploit prediction: 1% (62nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-611
Affected product: Antennahouse Office Server Document Converter
Published: 2021-11-01
Last modified: 2026-06-17

Description

Office Server Document Converter V7.2MR4 and earlier and V7.1MR7 and earlier allows a remote unauthenticated attacker to conduct an XML External Entity (XXE) attack to cause a denial of service (DoS) condition to the other servers by processing a specially crafted XML document.

Frequently asked questions

What is CVE-2021-20839?: Office Server Document Converter V7.2MR4 and earlier and V7.1MR7 and earlier allows a remote unauthenticated attacker to conduct an XML External Entity (XXE) attack to cause a denial of service (DoS) condition to the other servers by processing a specially crafted XML document.
How severe is CVE-2021-20839?: CVE-2021-20839 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-20839 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20839?: CVE-2021-20839 primarily affects Antennahouse Office Server Document Converter. In total, 23 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-20839?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-20839 published?: CVE-2021-20839 was published on 2021-11-01 and last updated on 2026-06-17.

References

Affected products (23)

cpe:2.3:a:antennahouse:office_server_document_converter:*:*:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:5.2:-:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:6.0:-:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:6.0:mr1:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:6.0:mr2:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:6.1:-:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:6.1:mr2:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:6.1:mr2:*:*:pro:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:6.1:mr3:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:6.1:mr4:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:7.0:*:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:7.0:mr1:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:7.0:mr2:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:7.0:mr3:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:7.1:-:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:7.1:mr1:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:7.1:mr2:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:7.1:mr3:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:7.2:*:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:7.2:mr1:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:7.2:mr2:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:7.2:mr3:*:*:*:*:*:*
cpe:2.3:a:antennahouse:office_server_document_converter:7.2:mr4:*:*:*:*:*:*

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CVE-2015-9280 — Critical (CVSS 10.0): MailEnable before 8.60 allows XXE via an XML document in the request.aspx Options parameter.
CVE-2018-1000838 — Critical (CVSS 10.0): autopsy version <= 4.9.0 contains a XML External Entity (XXE) vulnerability in CaseMetadata XML Parser that can result…
CVE-2018-1000837 — Critical (CVSS 10.0): UML Designer version <= 8.0.0 contains a XML External Entity (XXE) vulnerability in XML parser for plugins that can…
CVE-2018-1000835 — Critical (CVSS 10.0): KeePassDX version <= 2.5.0.0beta17 contains a XML External Entity (XXE) vulnerability in kdbx file parser that can…

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