CVE-2021-3199Public exploitNetwork attack vector

Remote code execution via image-path traversal

Published Jan 22, 2021 · Updated Aug 3, 2024

Path traversal in ONLYOFFICE Document Server before 5.6.3 allows remote attackers to execute code through a crafted image upload. The JWT-protected /upload handler accepts an ENCRYPTED payload containing /../ sequences, allowing uploaded bytes to overwrite a file outside the upload directory. The affected configuration uses JWT; the public PoC overwrites the docbuilder executable and invokes /docbuilder to execute code as the service account.

CVSS severity9.8
Critical
EPSS probability8.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in ONLYOFFICE Document Server before 5.6.3 allows remote attackers to execute code through a crafted image upload. The JWT-protected /upload handler accepts an ENCRYPTED payload containing /../ sequences, allowing uploaded bytes to overwrite a file outside the upload directory. The affected configuration uses JWT; the public PoC overwrites the docbuilder executable and invokes /docbuilder to execute code as the service account.

The record

CVE
CVE-2021-3199
Published
Jan 22, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-22, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 22, 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?

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

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

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 exploitPublished

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
T1190Exploit Public-Facing Application

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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