A missing input validation in Nextcloud Server before 20.0.2, 19.0.5, 18.0.11 allows users to store unlimited data in workflow rules causin…

published 2021-01-26 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-29161

cvss: 6.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.6%; EPSS 1.6% chance of exploitation in 30 days, percentile 75%
public exploits: 0; none known

A missing input validation in Nextcloud Server before 20.0.2, 19.0.5, 18.0.11 allows users to store unlimited data in workflow rules causing load and potential DDoS on later interactions and usage with those rules.

Patch / fix

fixed in 1 distros 1

nextcloud nextcloud_server 18.0.11, 19.0.5, 20.0.2

nextcloud Package Hub 15 SP3, Package Hub 15 SP2, Package Hub 15 SP1 +3 more 20.0.11-bp153.2.3.1
nextcloud Package Hub 15 SP2 20.0.7-bp152.2.6.1
nextcloud openSUSE Leap 15.2 20.0.7-lp152.3.6.1

opensuse advisories openSUSE-SU-2021:1068-1 openSUSE-SU-2021:0274-1 openSUSE-SU-2021:0262-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-8293 updated 2025-11-21 cvss 5.1

nextcloud: input validation issue allows users to store unlimited data in workflow rules

Red Hat All currently supported Red Hat products
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.58% chance of exploitation in the next 30 days, higher than 75% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD	2.0	4.0	AV:N/AC:L/Au:S/C:N/I:N/A:P

Affected products

n/a Nextcloud Server

Classification

Weakness

CWE-400 Uncontrolled Resource Consumption

References

nextcloud.com /security/advisory/?id=NC-SA-2021-001
broken-link, vendor-advisory
hackerone.com /reports/1018146
third-party-advisory

Sources

CVE List CVE-2020-8293
NVD CVE-2020-8293

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary