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CVE-2020-17518

Apache Flink directory traversal attack: remote file writing through the REST API

HIGH
7.5
CVSS Score
Published: January 5, 2021 at 11:40 AM UTC
Updated: June 17, 2026 at 02:59 AM UTC
1 product affected across 1 vendorFlink

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Severity
HIGH7.5
Exploit prediction
EPSS 49%

Description

Apache Flink 1.5.1 introduced a REST handler that allows you to write an uploaded file to an arbitrary location on the local file system, through a maliciously modified HTTP HEADER. The files can be written to any location accessible by Flink 1.5.1. All users should upgrade to Flink 1.11.3 or 1.12.0 if their Flink instance(s) are exposed. The issue was fixed in commit a5264a6f41524afe8ceadf1d8ddc8c80f323ebc4 from apache/flink:master.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Flink· Apache
95%
v ≤ 1.11.21.5.1 ≤ v < 1.11.3
Affected range stops below 1.11.3, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (24)

Mailing Listx_refsource_MLISTThird Party Advisory
Source: [email protected]
http://www.openwall.com/lists/oss-security/2021/01/05/1
Mailing Listx_refsource_MLIST
Source: [email protected]
https://lists.apache.org/thread.html/r0b000dc028616d33cb9aa388eb45d516b789cab0024dad94bc06588a%40%3Cissues.flink.apache.org%3E
Mailing Listx_refsource_MLIST
Source: [email protected]
https://lists.apache.org/thread.html/r1125f3044a0946d1e7e6f125a6170b58d413ebd4a95157e4608041c7%40%3Cannounce.apache.org%3E
Mailing Listx_refsource_MLIST
Source: [email protected]
https://lists.apache.org/thread.html/r229167538863518738e02f4c1c5a8bb34c1d45dadcc97adf6676b0c1%40%3Cdev.flink.apache.org%3E
x_refsource_MISC
Source: [email protected]
https://lists.apache.org/thread.html/r26fcdd4fe288323006253437ebc4dd6fdfadfb5e93465a0e4f68420d%40%3Cuser-zh.flink.apache.org%3E
Mailing Listx_refsource_MLIST
Source: [email protected]
https://lists.apache.org/thread.html/r28f17e564950d663e68cc6fe75756012dda62ac623766bb9bc5e7034%40%3Cissues.flink.apache.org%3E
Mailing Listx_refsource_MLIST
Source: [email protected]
https://lists.apache.org/thread.html/r4a87837518804b31eb9db3048347ed2bb7b46fbaad5844f22a9fd4dc%40%3Cissues.flink.apache.org%3E
Mailing Listx_refsource_MLIST
Source: [email protected]
https://lists.apache.org/thread.html/r5444acac3407ef6397d6aef1b5aec2db53b4b88ef221e63084c1e5f2%40%3Cissues.flink.apache.org%3E

CVSS

7.5HIGH[email protected]
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-23CWE-22

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