8.1

CVE-2023-21556: Windows Layer 2 Tunneling Protocol (L2TP) Remote Code Execution Vulnerability

Modified
Published 10-01-2023Last modified 01-01-2025

Vulnerability summary

CVE-2023-21556 is a high (CVSS 8.1) Integer Underflow (Wrap or Wraparound) vulnerability in microsoft windows_10_1607. EPSS estimates a 1.50% chance of exploitation in the next 30 days, higher than 74.1% of scored vulnerabilities.

Overall risk
33/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.1/10
010
High · v3.1 (CVE.org)
EPSS score
1.50%
0%100%
Low · +0.04 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 10-01-2023
    PublishedVulnerability first disclosed.
  2. 01-01-2025
    Last modifiedVulnerability information updated.

Description

Windows Layer 2 Tunneling Protocol (L2TP) Remote Code Execution Vulnerability

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

1.50%

Chance of exploitation in the next 30 days

Percentile

74%

Versus all other CVEs

30-day change

Increase +0.04 pp

From 1.46% on 22-09-2026

22-09-202622-10-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Microsoft34 products

1 vendor · 34 products

References

1 links