CVE-2021-43444Public exploitNetwork attack vector

Unauthorized document downloads via default signing key

Published Jan 23, 2023 · Updated Apr 2, 2025

Improper authentication in ONLYOFFICE Server 7.0.0.49 and earlier allows remote attackers to download documents through forged signed URLs. Document-data download URLs use MD5 signatures keyed with the default value "verysecretstring," making valid signatures reproducible. A known document identifier is required, but no session or WebSocket access is needed to retrieve the unencrypted document.

CVSS severity7.5
High
EPSS probability1.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication in ONLYOFFICE Server 7.0.0.49 and earlier allows remote attackers to download documents through forged signed URLs. Document-data download URLs use MD5 signatures keyed with the default value "verysecretstring," making valid signatures reproducible. A known document identifier is required, but no session or WebSocket access is needed to retrieve the unencrypted document.

The record

CVE
CVE-2021-43444
Published
Jan 23, 2023
Updated
Apr 2, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-287, T1213
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 23, 2023CVE publishedPublication date reported by the CVE source.
  2. Apr 2, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-287Improper Authentication
T1213Data from Information Repositories

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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