CVE-2020-17518Network attack vector

Arbitrary file write via multipart filename traversal

Published Jan 5, 2021 · Updated Feb 13, 2025

Path traversal in Apache Flink 1.5.1 through 1.11.2 allows remote attackers to write uploaded files through the REST API. FileUploadHandler resolves the multipart Content-Disposition filename against its upload directory without stripping path components. An exposed, unauthenticated REST interface is sufficient, and writes are limited to filesystem locations accessible to the Flink process.

CVSS severity7.5
High
EPSS probability50.04%
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 Apache Flink 1.5.1 through 1.11.2 allows remote attackers to write uploaded files through the REST API. FileUploadHandler resolves the multipart Content-Disposition filename against its upload directory without stripping path components. An exposed, unauthenticated REST interface is sufficient, and writes are limited to filesystem locations accessible to the Flink process.

The record

CVE
CVE-2020-17518
Published
Jan 5, 2021
Updated
Feb 13, 2025
Vendor
The Apache Software Foundation
Product
Apache Flink
Classifications
CWE-22, CWE-23, T1105
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 5, 2021CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 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?

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

  1. Affected versionversion=Apache Flink 1.5.1 to 1.11.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Flinkversion=Apache Flink 1.5.1 to 1.11.2

Published CVSS scores

7.5GitHub Advisory DatabaseCVSS: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.

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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 exploitUnconfirmed

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-23Relative Path Traversal
T1105Ingress Tool Transfer

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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