Skip to content
Noroxi
NVD / CVE Program· CNA GitHub_M

CVE-2021-32802: Preview generation used third-party library not suited for user-generated content in Nextcloud server

Noroxi assessment

Priority: Plan (action score 40/100)

  • 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: 2.6% (FIRST EPSS); higher than 85.4% 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) 20.0.12-lp152.3.12.1; nextcloud (openSUSE:Leap 15.3) 20.0.12-bp153.2.6.1; nextcloud (SUSE:Package Hub 12) 20.0.12-31.1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Add it to your regular patch cycle. Upgrade to nextcloud (openSUSE:Leap 15.2) 20.0.12-lp152.3.12.1; nextcloud (openSUSE:Leap 15.3) 20.0.12-bp153.2.6.1; nextcloud (SUSE:Package Hub 12) 20.0.12-31.1 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

Nextcloud server is an open source, self hosted personal cloud. Nextcloud supports rendering image previews for user provided file content. For some image types, the Nextcloud server was invoking a third-party library that wasn't suited for untrusted user-supplied content. There are several security concerns with passing user-generated content to this library, such as Server-Side-Request-Forgery, file disclosure or potentially executing code on the system. The risk depends on your system configuration and the installed library version. It is recommended that the Nextcloud Server is upgraded to 20.0.12, 21.0.4 or 22.1.0. These versions do not use this library anymore. As a workaround users may disable previews by setting `enable_previews` to `false` in `config.php`.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Sep 7, 2021
Updated
Jun 16, 2026
EPSS
2.6% · 85th percentile

Report tools

JSON

Action score

40

Plan

Add it to your regular patch cycle.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 2.6%

CNA vs NVD score

NVD
9.8
CNA · GitHub_M
9.3
0.5 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-32802

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

Your free account also gets you

Running WordPress? Scan your site free with WP Lens

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for nextcloud records

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

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.

We use this product, ask for help

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.

VendorProduct
nextcloudnextcloud 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 20.0.12
  • nextcloud nextcloud server21.0.0 and later · before 21.0.4
  • nextcloud nextcloud server22.0.0 and later · before 22.1.0

Versions reported by the vendor

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

  • nextcloud security-advisories

    • < 20.0.12, >= 21.0.0, < 21.0.4, >= 22.0.0, < 22.1.0affected

Package-level exposure

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

EcosystemPackageAffected rangeFix
openSUSE:Leap 15.2nextcloudbefore 20.0.12-lp152.3.12.120.0.12-lp152.3.12.1
openSUSE:Leap 15.3nextcloudbefore 20.0.12-bp153.2.6.120.0.12-bp153.2.6.1
SUSE:Package Hub 12nextcloudbefore 20.0.12-31.120.0.12-31.1
SUSE:Package Hub 15 SP1nextcloudbefore 20.0.12-bp151.3.18.120.0.12-bp151.3.18.1
SUSE:Package Hub 15 SP2nextcloudbefore 20.0.12-bp152.2.12.120.0.12-bp152.2.12.1
SUSE:Package Hub 15 SP3nextcloudbefore 20.0.12-bp153.2.6.120.0.12-bp153.2.6.1

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-2021-32726Webauthn tokens not removed after user has been deleted
    40Plan
  • CVE-2021-22915Nextcloud server before 19.0.11, 20.0.10, 21.0.2 is vulnerable to brute force attacks due to lack of inclusion of IPv6 subnets in rate-limit
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2021-32800Sep 7, 2021 · Bypass of Two Factor Authentication in Nextcloud server
    33Monitor
  • ← EarlierCVE-2021-32801Sep 7, 2021 · Exceptions may have logged Encryption-at-Rest key content in Nextcloud server
    22Monitor
  • Later →CVE-2021-41177Oct 25, 2021 · Rate-limits not working on instances without configured memory cache backend
    32Monitor

Remediation

Which version to upgrade to

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

Product / packageFixed versionSource
opensuse:nextcloud20.0.12-bp153.2.6.1 · openSUSE:Leap 15.3Package registry (OSV)
opensuse:nextcloud20.0.12-lp152.3.12.1 · openSUSE:Leap 15.2Package registry (OSV)
suse:nextcloud20.0.12-bp151.3.18.1 · SUSE:Package Hub 15 SP1Package registry (OSV)
suse:nextcloud20.0.12-bp153.2.6.1 · SUSE:Package Hub 15 SP3Package 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.

No history yet (it accumulates with the daily EPSS job).

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

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.

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
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-829 · Inclusion of Functionality from Untrusted Control Sphere

CVSS vector

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

nvd-primary

Attack context

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

Change log

  1. Fix✗ → ✓

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

References

Show all references (3 more)

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

All records