CVE-2021-21245Network attack vector

Unauthenticated arbitrary file write via filename traversal

Published Jan 15, 2021 · Updated Aug 3, 2024

Arbitrary file upload in OneDev before 4.0.3 allows remote attackers to write files anywhere the server process has permission to write. AttachmentUploadServlet URL-decodes the File-Name header without removing traversal segments, then passes it and the request body to saveAttachment. No authentication or authorization check precedes the write; uploaded data is not executed when confined to the attachments directory.

CVSS severity9.8
Critical
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

Arbitrary file upload in OneDev before 4.0.3 allows remote attackers to write files anywhere the server process has permission to write. AttachmentUploadServlet URL-decodes the File-Name header without removing traversal segments, then passes it and the request body to saveAttachment. No authentication or authorization check precedes the write; uploaded data is not executed when confined to the attachments directory.

The record

CVE
CVE-2021-21245
Published
Jan 15, 2021
Updated
Aug 3, 2024
Vendor
OneDev Pty
Product
OneDev
Classifications
CWE-434, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.0.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OneDev Pty · OneDevversion=< 4.0.3

Published CVSS scores

10.0GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N
7.5NISTAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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-434Unrestricted Upload of File with Dangerous Type
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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