CVE-2021-21974

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National Vulnerability Database Information

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.

CVSS Base Score: 8.8 (v3.1)

The CVSS Base Score is a score from 0 to 10 that represents the intrinsic severity of a vulnerability. A higher score indicates greater severity.

Value

0.02.55.07.510.0

Published on: 02/24/2021 17:15:16
Last modified: 06/17/2026 03:36:29
NIST: CVE source from the National Vulnerability Database (NVD)

CVSS Metrics Details

Base Severity: HIGH
Vector String: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector: ADJACENT_NETWORK
Attack Complexity: LOW
Privileges Required: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality Impact: HIGH
Integrity Impact: HIGH
Availability Impact: HIGH

Common Weakness Enumeration (CWE)

Database CWE: v4.18

CWE-787: Out-of-bounds Write ↗

The product writes data past the end, or before the beginning, of the intended buffer.

Fonte: MITRE CWE

FIRST Information

EPSS Score: 0.4506

The EPSS (Exploit Prediction Scoring System) is a score from 0 to 1 that indicates the probability that a vulnerability will be exploited in the real world in the next 30 days. A higher value indicates a greater likelihood of exploitation.

Value

0.00.250.50.751.0

Percentile: 0.9871

The Percentile indicates how much higher this vulnerability's EPSS score is compared to all other vulnerabilities in the EPSS database. For example, a percentile of 0.90 (90%) means that 90% of vulnerabilities have an EPSS score equal to or lower than the current one.

Value

0.00.250.50.751.0

*Data updated as of: 2026-09-12

CISA Information (Known Exploited Vulnerabilities)

The CISA KEV Catalog lists vulnerabilities that have been actively exploited in the real world. If a CVE is present in this catalog, it indicates that the threat is immediate and mitigation should be a top priority.

CVE CVE-2021-21974 is not present in the CISA KEV Catalog. This indicates that it is not currently classified by CISA as an actively exploited vulnerability.

Articles published on Red Hot Cyber

NVD References

Exploit PoC from GitHub

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