Security Resilience

CVE-2023-27516

Softether Vpn 4.41-9782 … 5.01.9674

Public PoC
Published
12 October 2023
Modified
21 November 2024
Patch / advisory
View advisory
CVSS Score v3.1 7.3
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
EPSS Score 0.0053 43th percentile
Risk Priority 55 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-27516 is a high-severity Insecure Default Variable Initialization (CWE-453) vulnerability in Softether Vpn. Its CVSS base score is 7.3 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Data Obfuscation (T1001); ranked at the 43th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability Data

An authentication bypass vulnerability exists in the CiRpcAccepted() functionality of SoftEther VPN 4.41-9782-beta and 5.01.9674. A specially crafted network packet can lead to unauthorized access. An attacker can send a network request to trigger this vulnerability.

CWE(s)
CWE-453CWE-1188

Related Threats

MITRE ATT&CK Enterprise Techniques

T1001 Data Obfuscation Command And Control
Adversaries may obfuscate command and control traffic to make it more difficult to detect.
attack.mitre.org →
T1001.001 Junk Data Command And Control
Adversaries may add junk data to protocols used for command and control to make detection more difficult.
attack.mitre.org →
T1001.002 Steganography Command And Control
Adversaries may use steganographic techniques to hide command and control traffic to make detection efforts more difficult.
attack.mitre.org →
T1001.003 Protocol or Service Impersonation Command And Control
Adversaries may impersonate legitimate protocols or web service traffic to disguise command and control activity and thwart analysis efforts.
attack.mitre.org →
T1003.002 Security Account Manager Credential Access
Adversaries may attempt to extract credential material from the Security Account Manager (SAM) database either through in-memory techniques or through the Windows Registry where the SAM database is stored.
attack.mitre.org →
T1003.004 LSA Secrets Credential Access
Adversaries with SYSTEM access to a host may attempt to access Local Security Authority (LSA) secrets, which can contain a variety of different credential materials, such as credentials for service accounts.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-25565Same product: Softether Vpn
CVE-2023-22308Same product: Softether Vpn
CVE-2025-25568Same product: Softether Vpn
CVE-2025-25567Same product: Softether Vpn
CVE-2023-23581Same product: Softether Vpn
CVE-2023-27395Same product: Softether Vpn
CVE-2023-32275Same product: Softether Vpn
CVE-2023-32634Same product: Softether Vpn
CVE-2025-25566Same product: Softether Vpn
CVE-2023-25774Same product: Softether Vpn

Affected Assets

softether
vpn
4.41-9782, 5.01.9674

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 15 hardening rules · 7 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V14.3.2
  • V6.3.2
  • V11.3.1
  • V13.2.3

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

CM-1 Policy and Procedures
addresses: CWE-1188

Requires documented secure initialization practices and avoidance of insecure defaults in configuration baselines.

CM-2 Baseline Configuration
addresses: CWE-1188

Reviewing and updating baseline when components are installed or upgraded prevents initialization with insecure defaults.

CM-7 Least Functionality
addresses: CWE-1188

Requiring explicit configuration to minimal functionality overrides insecure defaults that would otherwise enable excess capabilities.

PL-11 Baseline Tailoring
addresses: CWE-1188

Tailoring replaces or augments insecure default initializations with system-specific values and compensating controls before deployment.

PL-9 Central Management
addresses: CWE-1188

Central configuration overrides or replaces insecure default initializations that would otherwise be left unchanged on each system.

PM-30 Supply Chain Risk Management Strategy
addresses: CWE-1188

SCRM practices during acquisition and configuration management address insecure default initializations shipped by vendors.

RA-5 Vulnerability Monitoring and Scanning
addresses: CWE-1188

Scans detect resources initialized with insecure defaults that create exploitable conditions.

SA-16 Developer-provided Training
addresses: CWE-1188

Instruction on secure initialization of security controls prevents leaving resources with insecure defaults after installation.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

ID.RA-09 partial match
blocks

Pre-acquisition integrity checks can reject products known to ship with insecure defaults.

PR.PS-01 partial match
blocks

Hardened baselines and configuration management directly replace insecure product defaults with secure values.

PR.PS-06 partial match
blocks

Secure software development practices explicitly include choosing safe initial values instead of insecure defaults.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.5.14 Information transfer partial match
removes
A.5.15 Access control partial match
removes
A.5.16 Identity management partial match
removes
A.5.17 Authentication information partial match
removes
A.5.18 Access rights partial match
removes
A.8.10 Information deletion partial match
removes

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (higher-evidence rows only; rows rated `none` are excluded).

Oracle Linux 8 (1 rule)
  • V-248823 OL 8 must not have the telnet-server package installed. blocks CWE-1188
RHEL 7 (1 rule)
  • V-204627 SNMP community strings on the Red Hat Enterprise Linux operating system must be changed from the default. blocks CWE-1188
Ubuntu 22.04 (1 rule)
  • V-260529 Ubuntu 22.04 LTS must be configured so that remote X connections are disabled, unless to fulfill documented and validated mission requirements. blocks CWE-1188
Ubuntu 24.04 (1 rule)
  • V-270708 Ubuntu 24.04 LTS must be configured so that remote X connections are disabled, unless to fulfill documented and validated mission requirements. blocks CWE-1188
Windows Server 2016 (1 rule)
  • V-224972 Active Directory Group Policy objects must have proper access control permissions. blocks CWE-1188
Windows Server 2019 (1 rule)
  • V-205741 Windows Server 2019 Active Directory Group Policy objects must have proper access control permissions. blocks CWE-1188

References