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ExploitedNot in CISA KEV yetFix available

CVE-2020-17518

Exploitation confirmed. First attested on 2023-10-15 by GCVE · kevintel, GCVE · shadowserver.

  • Published2021-01-05
  • Fixed in1.11.3
  • WeaknessCWE-22 · CWE-23

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2021-01-0512:15CVE publishedNVD
  2. 2023-10-1501:09Listed as exploited by GCVEGCVE
  3. 2023-10-1501:09Exploitation first reportedGCVE

Observed activity

isMalicious corpus · updated 2026-11-03 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-17518?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-17518?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV
Apache flink
BranchAffectedFixed in
1.x≥ 1.5.1, < 1.11.31.11.3

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • CVE-2020-17518 Red Hat Product Security3 products fixed

    apache-flink: directory traversal attack allows remote file writing through the REST API

  • RHSA-2021:3207 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat Integration Camel Quarkus Tech-Preview 2 security update

  • RHSA-2021:3205 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat Integration Camel-K 1.4 release and security update

  • RHSA-2021:3140 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: Red Hat Fuse 7.9.0 release and security update

Full record on NVD

Fix

  1. Update Apache flink to 1.11.3
  2. Vendor fix Red Hat Product Security RHSA-2021:3207 · 1 productBefore applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
  3. Vendor fix Red Hat Product Security RHSA-2021:3205 · 1 productBefore applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
  4. Vendor fix Red Hat Product Security RHSA-2021:3140 · 1 productBefore applying the update, back up your existing installation, including all applications, configuration files, databases and database settings, and so on. Installation instructions are available from the Fuse 7.9.0 product documentation page: https://access.redhat.com/documentation/en-us/red_hat…

Advisories and patches

Detection

read 2026-11-02 22:42 UTC
Nuclei template
available
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
3 repositories, unverifiedQmF0c3UK/CVE-2020-17518murataydemir/CVE-2020-17518rakjong/Flink-CVE-2020-17518-getshell
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Published
2021-01-05
Last Modified
2026-06-17
NVD status
Modified
GitHub Advisory
GHSA-7q5g-gph2-4rc6

Frequently asked questions

What is CVE-2020-17518?

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.

Is CVE-2020-17518 actively exploited?

Active exploitation of CVE-2020-17518 has not been confirmed. Its EPSS score was 49.1% on 2026-11-03, the estimated probability of exploitation in the next 30 days.

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

CVE-2020-17518 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.

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