How severe is CVE-2021-21978?

No CVSS score has been assigned to CVE-2021-21978 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2021-21978?

Affected package information for CVE-2021-21978 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2021-21978?

No fixed release is recorded for CVE-2021-21978 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

How do I detect CVE-2021-21978 in my code and dependencies?

Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

How do I mitigate CVE-2021-21978 if there is no patch (or I can't update yet)?

Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Is CVE-2021-21978 actively exploited in the wild?

Yes. There are 8 known exploit references for CVE-2021-21978, including 5 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-21978?

CVE-2021-21978 has an EPSS (Exploit Prediction Scoring System) score of 99.0%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

What type of vulnerability is CVE-2021-21978?

CVE-2021-21978 is classified as Improper Input Validation (CWE-20), CWE-862 (CWE-862). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Is there exploit tooling available for CVE-2021-21978?

A Nuclei detection template exists for CVE-2021-21978, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2021-21978 published, and has it been updated?

CVE-2021-21978 was published on March 3, 2021 and was last updated on August 3, 2024. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

Not in CISA KEV

CVE-2021-21978

CVE-2021-21978 is a Improper Input Validation vulnerability. 8 public exploit references exist, so weaponization risk is real. No vendor fix is recorded yet; mitigation options are listed below.

VMware View Planner 4.x prior to 4.6 Security Patch 1 contains a remote code execution vulnerability. Improper input validation and lack of authorization leading to arbitrary file upload…

Published

Mar 3, 2021

Updated

Aug 3, 2024

Affected

1 product

Patched

See advisory

Exploits

8 known

Exploitation data as of Oct 23, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

99.0%probability of exploitation in next 30 days

Very High Risk0.00%

Lower risk than most CVEs100th percentile — riskier than 100% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Description

VMware View Planner 4.x prior to 4.6 Security Patch 1 contains a remote code execution vulnerability. Improper input validation and lack of authorization leading to arbitrary file upload in logupload web application. An unauthorized attacker with network access to View Planner Harness could upload and execute a specially crafted file leading to remote code execution within the logupload container.

Affected Products

1 product · 2 configurations

Application

view plannervmware

≥ 4.0 && < 4.6

1 version

4.6

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.