CVE-2021-21974: OpenSLP as used in ESXi (7.0 before ESXi70U1c-17325551, 6.7 before ESXi670-202102401-SG, 6.5 before ESXi650-202102101…
- Is it exploited?
Reported, not confirmed by CISA. VulnCheck KEV lists it as exploited in the wild. CISA has not added it to its Known Exploited Vulnerabilities catalog as of .
VulnCheck KEV lists it since . It cites 15 public reports, the first from .
- How likely is exploitation in the next 30 days?
- 45.1%
EPSS score, percentile 98.8 of all scored records. A probability estimated by FIRST, not a report of exploitation.
CISA's SSVC assessment in the CVE record lists exploitation as poc.
- How severe?
- 8.8 High
CVSS v3.1 base score, from CISA's enrichment of the record
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- 7.0 before ESXi70U1c-17325551
- 6.7 before ESXi670-202102401-SG
- 6.5 before ESXi650-202102101-SG
- 4.x before 4.2 and 3.x
Source: CISA KEV 2026.10.29, as of ; VulnCheck KEV, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
Description
OpenSLP as used in ESXi (7.0 before ESXi70U1c-17325551, 6.7 before ESXi670-202102401-SG, 6.5 before ESXi650-202102101-SG) has a heap-overflow vulnerability. A malicious actor residing within the same network segment as ESXi who has access to port 427 may be able to trigger the heap-overflow issue in OpenSLP service resulting in remote code execution.
Source: CVE List, as of . About the data.
What to do
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
Versions by product, as listed in the CVE record (2 products)
| Status | Versions |
|---|---|
| Affected | 7.0 before ESXi70U1c-17325551 |
| Affected | 6.7 before ESXi670-202102401-SG |
| Affected | 6.5 before ESXi650-202102101-SG |
| Status | Versions |
|---|---|
| Affected | 4.x before 4.2 and 3.x |
Source: CVE List, as of . About the data.
Weakness
CWE-787
- CWE-787: Out-of-bounds Write
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| CVE record last updated |
Known exploited VMware vulnerabilities
- CVE-2025-22224: VMware ESXi and Workstation TOCTOU Race Condition Vulnerability
- CVE-2025-22225: VMware ESXi Arbitrary Write Vulnerability
- CVE-2025-22226: VMware ESXi, Workstation, and Fusion Information Disclosure Vulnerability
- CVE-2024-38812: VMware vCenter Server Heap-Based Buffer Overflow Vulnerability
- CVE-2024-38813: VMware vCenter Server Privilege Escalation Vulnerability