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Public proof of conceptFix available

CVE-2020-13664

A public proof of concept exists; no exploitation attested.

  • Published2021-05-05
  • Fixed in9.0.1 · 8.9.1 · 8.8.8
  • WeaknessCWE-77

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

Arbitrary PHP code execution vulnerability in Drupal Core under certain circumstances. An attacker could trick an administrator into visiting a malicious site that could result in creating a carefully named directory on the file system. With this directory in place, an attacker could attempt to brute force a remote code execution vulnerability. Windows servers are most likely to be affected. This issue affects: Drupal Drupal Core 8.8.x versions prior to 8.8.8; 8.9.x versions prior to 8.9.1; 9.0.1 versions prior to 9.0.1.

Timeline

dates in UTC
  1. 2021-05-0515:15CVE publishedNVD
  2. 2026-10-2319:23First public proof of conceptPoC-in-GitHub

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 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-2020-13664?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-13664?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Drupal
BranchAffectedFixed in
9.0≥ 9.0.0, < 9.0.19.0.1
8.9≥ 8.9.0, < 8.9.18.9.1
8.8≥ 8.8.0, < 8.8.88.8.8

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

Fix

  1. Update Drupal to 9.0.1 · 8.9.1 · 8.8.8

Advisories and patches

Detection

read 2026-10-23 19:23 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
1 repository, unverifiedlorenzog/CVE-2020-13664
PoC-in-GitHub

Sources

  • NVDCVSS 3.18.8read 2026-10-23
  • NVDCVSS 2.09.3read 2026-10-23
  • NVDweakness (CWE)CWE-77read 2026-10-23
  • FIRST EPSSEPSS score3.0 %2026-10-22
  • PoC-in-GitHubproof of concept1read 2026-10-23

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published
2021-05-05
Last Modified
2026-06-17
NVD status
Modified

Frequently asked questions

What is CVE-2020-13664?

Arbitrary PHP code execution vulnerability in Drupal Core under certain circumstances. An attacker could trick an administrator into visiting a malicious site that could result in creating a carefully named directory on the file system. With this directory in place, an attacker could attempt to brute force a remote code execution vulnerability. Windows servers are most likely to be affected. This issue affects: Drupal Drupal Core 8.8.x versions prior to 8.8.8; 8.9.x versions prior to 8.9.1; 9.0.1 versions prior to 9.0.1.

Is CVE-2020-13664 actively exploited?

Active exploitation of CVE-2020-13664 has not been confirmed. Its EPSS score was 3.0% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-13664?

CVE-2020-13664 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

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