NVD / CVE Program· CNA hackerone

CVE-2020-8295: A wrong check in Nextcloud Server 19 and prior allowed to perform a denial of service attack when resetting the password for a user.

Noroxi assessment

Priority: Monitor (action score 31/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 1.8% (FIRST EPSS); higher than 78.6% of all records.
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
Fixed version: nextcloud (openSUSE:Leap 15.2) 20.0.7-lp152.3.6.1, 20.0.11-bp153.2.3.1; nextcloud (SUSE:Package Hub 12) 20.0.11-bp153.2.3.1; nextcloud (SUSE:Package Hub 15 SP2) 20.0.7-bp152.2.6.1.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to nextcloud (openSUSE:Leap 15.2) 20.0.7-lp152.3.6.1, 20.0.11-bp153.2.3.1; nextcloud (SUSE:Package Hub 12) 20.0.11-bp153.2.3.1; nextcloud (SUSE:Package Hub 15 SP2) 20.0.7-bp152.2.6.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

HighCVSS 7.5 · v3.1—No exploit Fix available

Published: Jan 26, 2021
Updated: Jun 16, 2026
EPSS: 1.8% · 78th percentile
CWE: CWE-400

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 1 / 30 · 1.8%

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
nextcloud	nextcloud server	cpe:2.3:a:nextcloud:nextcloud_server

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

nextcloud nextcloud serverbefore 20.0.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (hackerone). Independent of NVD's CPE analysis and usually ahead of it.

n/a Nextcloud Server
- Fixed in 20.0.0affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
openSUSE:Leap 15.2	nextcloud	before 20.0.7-lp152.3.6.1	20.0.7-lp152.3.6.1
openSUSE:Leap 15.2	nextcloud	before 20.0.11-bp153.2.3.1	20.0.11-bp153.2.3.1
SUSE:Package Hub 12	nextcloud	before 20.0.11-bp153.2.3.1	20.0.11-bp153.2.3.1
SUSE:Package Hub 15 SP2	nextcloud	before 20.0.7-bp152.2.6.1	20.0.7-bp152.2.6.1

Same product

nextcloud: all records

Other highest-scoring records for the same primary product.

CVE-2023-26482Scope of workflow operations is not validated in nextcloud server
40Plan
CVE-2021-32802Preview generation used third-party library not suited for user-generated content in Nextcloud server
40Plan
CVE-2021-32726Webauthn tokens not removed after user has been deleted
40Plan

Published before and after this one in the same product

← EarlierCVE-2020-8259Nov 15, 2020 · Insufficient protection of the server-side encryption keys in Nextcloud Server 19.0.1 allowed an attacker to replace the encryption keys.
32Monitor
← EarlierCVE-2020-8293Jan 26, 2021 · 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
26Monitor
Later →CVE-2020-8294Feb 3, 2021 · A missing link validation in Nextcloud Server before 20.0.2, 19.0.5, 18.0.11 allows execution of a stored XSS attack using Internet Explorer
21Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
opensuse:nextcloud	20.0.11-bp153.2.3.1 · openSUSE:Leap 15.2	Package registry (OSV)
opensuse:nextcloud	20.0.7-lp152.3.6.1 · openSUSE:Leap 15.2	Package registry (OSV)
suse:nextcloud	20.0.11-bp153.2.3.1 · SUSE:Package Hub 12	Package registry (OSV)
suse:nextcloud	20.0.7-bp152.2.6.1 · SUSE:Package Hub 15 SP2	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

NextcloudHackerOne · paid

The product’s vendor appears in a public program. Matched by name; verify the scope text in the program.

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

TR-21-0068 · Jan 26, 2021(Nextcloud Zafiyeti)

All national notices →

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: none
Integrity: none
Availability: high · the service can be disrupted

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: None
Integrity impact: None
Availability impact: High

Weakness class (CWE)

CWE-400 · Uncontrolled Resource Consumption

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

The bug in code

The whole CWE-400 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1function expand(node) {
2  return node.children.map(expand);
3}

Fixed

1const MAX_DEPTH = 32;
2function expand(node, depth = 0) {
3  if (depth > MAX_DEPTH) throw new Error("too deep");
4  return node.children.map((c) => expand(c, depth + 1));
5}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

Endpoint Denial of ServiceT1499

Change log

Fix✗ → ✓Sep 28, 2026, 10:47 PM UTC

For records you follow, these changes also arrive as notifications. →

References

nextcloud.com/security/advisory/?id=NC-SA-2021-003

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records