CVE-2020-13671
CVE-2020-13671 is a security flaw in Drupal core, software for building and running websites. Attackers are using a flaw in Drupal core. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 18 Jan 2022.[1]
Drupal core is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Drupal has published a fix or advice.
Description
CISA calls it a core un-restricted upload of file in Drupal Drupal core. In its words: “Improper sanitization in the extension file names is present in Drupal core.”[1]
The CVE record adds: “Drupal core does not properly sanitize certain filenames on uploaded files, which can lead to files being interpreted as the incorrect extension and served as the wrong MIME type or executed as PHP for certain hosting configurations. This issue affects: Drupal Drupal Core 9.0 versions prior to 9.0.8, 8.9 versions prior to 8.9.9, 8.8 versions prior to 8.8.11, and 7 versions prior to 7.74.”[2]
The underlying weakness is unrestricted file upload (CWE-434), in MITRE’s list of common software weaknesses.
It scores 8.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Drupal’s advisory has them[3]. CISA names the product as Drupal Drupal core.
Most families won’t have Drupal core; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 18 Jan 2022, 424 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 18 Jul 2022 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 36%. That’s in the top 2% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Drupal has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Check whether you use it.Drupal core is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 18 Jul 2022 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 8.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 36%.[4] |
See also
Other Drupal flaws
- CVE-2026-9082, Drupal Core: SQL injection ·
- CVE-2018-7602, Drupal Core: remote code execution ·
- CVE-2019-6340, Drupal Core: remote code execution ·
- CVE-2018-7600, Drupal Core: core remote code execution ·
Other unrestricted file upload flaws
- CVE-2026-48356, Adobe Commerce and Magento: unrestricted upload of file with dangerous type ·
- CVE-2026-56291, Balbooa Forms: unrestricted upload of file with dangerous type ·
- CVE-2026-48939, iCagenda: unrestricted upload of file with dangerous type ·
- CVE-2026-48908, JoomShaper SP Page Builder: unrestricted upload of file with dangerous type ·
- CVE-2024-7694, TeamT5 ThreatSonar Anti-Ransomware: unrestricted upload of file with dangerous type ·
Added the same day
- CVE-2021-40870, Aviatrix Controller: controller unrestricted upload of file ·
- CVE-2021-33766, Microsoft Exchange Server: information disclosure ·
- CVE-2021-32648, October CMS: improper authentication ·
- CVE-2021-25298, Nagios XI: XI OS command injection ·
- CVE-2021-25297, Nagios XI: XI OS command injection ·
Every Drupal flaw on CISA’s list · Everything added in January 2022
References
- ^ Cybersecurity and Infrastructure Security Agency. “Drupal core Un-restricted Upload of File”. Known Exploited Vulnerabilities Catalog, added 18 Jan 2022.
- ^ National Institute of Standards and Technology. “CVE-2020-13671 Detail”. National Vulnerability Database, published 20 Nov 2020.
- ^ Drupal. Advisories and fixes: lists.fedoraproject.org, lists.fedoraproject.org, drupal.org.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.362, percentile 98.5, 31 Oct 2026.
- CVE Program. “CVE-2020-13671”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.