Is CVE-2020-17518 actively exploited?

Yes. CVE-2020-17518 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, which means exploitation in the wild has been confirmed.

Can CVE-2020-17518 be exploited remotely?

The attack vector of CVE-2020-17518 has not been classified yet.

What is the CVSS score of CVE-2020-17518?

CVE-2020-17518 has not received a CVSS score yet.

HOME VULNERABILITIESCVE-2020-17518

UNKNOWNCISA KEVIN THE WILD

CVE-2020-17518

Published: April 11, 2026

EPSS:93.79%probability of exploitation in 30 daysPercentile:99.9th

Official 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.

NVD Source

Technical Analysis

CVE-2020-17518 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

CISA has added CVE-2020-17518 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.