CVE-2020-28645Network attack vector

System file deletion via invalid usernames

Published Feb 9, 2021 · Updated Aug 4, 2024

Improper input validation in ownCloud core before 10.6 allows remote attackers to delete system files via crafted usernames. The user-deletion path fails to reject reserved usernames that resolve to system paths, so deleting such an account removes those files. Exploitation requires a reachable ownCloud account-deletion interface; self-registration and a data directory under the web root increase risk, while impact is file integrity and service availability.

CVSS severity9.1
Critical
EPSS probability1.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper input validation in ownCloud core before 10.6 allows remote attackers to delete system files via crafted usernames. The user-deletion path fails to reject reserved usernames that resolve to system paths, so deleting such an account removes those files. Exploitation requires a reachable ownCloud account-deletion interface; self-registration and a data directory under the web root increase risk, while impact is file integrity and service availability.

The record

CVE
CVE-2020-28645
Published
Feb 9, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-20
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 9, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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

3.1ownCloudCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N
9.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation

Public exploit references

No public exploit references are available in this record.

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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