Cyber Resilience

CVE-2023-20240

Memory Safety in Cisco Secure Client 4.10.00093 … 5.0.03076

Memory Safety
Published
22 November 2023
Modified
21 November 2024
Patch / advisory
View advisory
CVSS Score v3.1 5.5
Click a component to see what it means
Raw vectorCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS Score 0.0020 10th percentile
Risk Priority 41 floored blend · peak EPSS

Summary

CVE-2023-20240 is a medium-severity Out-of-bounds Read (CWE-125) vulnerability in Cisco Secure Client. Its CVSS base score is 5.5 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 10th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability Data

Multiple vulnerabilities in Cisco Secure Client Software, formerly AnyConnect Secure Mobility Client, could allow an authenticated, local attacker to cause a denial of service (DoS) condition on an affected system. These vulnerabilities are due to an out-of-bounds memory read from…

more

Cisco Secure Client Software. An attacker could exploit these vulnerabilities by logging in to an affected device at the same time that another user is accessing Cisco Secure Client on the same system, and then sending crafted packets to a port on that local host. A successful exploit could allow the attacker to crash the VPN Agent service, causing it to be unavailable to all users of the system. To exploit these vulnerabilities, the attacker must have valid credentials on a multi-user system.

CWE(s)
CWE-125

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1211 Exploitation for Stealth Stealth
Adversaries may exploit vulnerabilities to evade detection by hiding activity, suppressing logging, or operating within trusted or unmonitored components.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2023-20241Same product: Cisco Anyconnect Secure Mobility Client
CVE-2024-20474Same product: Cisco Anyconnect Secure Mobility Client
CVE-2023-20178Same product: Cisco Anyconnect Secure Mobility Client
CVE-2020-3153Same product: Cisco Anyconnect Secure Mobility Client
CVE-2020-3433Same product: Cisco Anyconnect Secure Mobility Client
CVE-2026-3055Same product class: VPN / SSL gateway
CVE-2025-20152Same vendor: Cisco
CVE-2024-46670Same product class: VPN / SSL gateway
CVE-2023-20094Same vendor: Cisco
CVE-2024-36504Same product class: VPN / SSL gateway

Affected Assets

cisco
anyconnect secure mobility client
4.9.00086, 4.9.01095, 4.9.02028, 4.9.03047, 4.9.03049
cisco
secure client
4.10.00093, 4.10.01075, 4.10.02086, 4.10.03104, 4.10.04065

Mitigating Controls

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.

PR.PS-06 mostly match
prevents

Secure-development practices such as bounds checking and memory-safe languages directly prevent out-of-bounds reads.

ID.RA-01 partial match
prevents

Vulnerability scanning and recording can discover instances of out-of-bounds reads after code is deployed.

PR.PS-02 partial match
prevents

Routine patching replaces vulnerable code containing out-of-bounds read flaws.

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.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development and acceptance includes fuzzing and static analysis that detect out-of-bounds read defects before release.

A.8.15 Logging partial match
finds

Logging can record evidence of an out-of-bounds read but does not prevent the weakness itself.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates input validation and bounds checking that directly prevent out-of-bounds reads.

A.8.26 Application security requirements partial match
prevents

Application security requirements include explicit bounds and memory-safety specifications that mitigate buffer over-reads.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure system architecture and engineering principles require memory-safe design patterns and runtime protections against out-of-bounds access.

A.8.28 Secure coding partial match
prevents

Secure coding standards explicitly forbid unsafe pointer arithmetic and mandate bounds-checked reads, eliminating CWE-125.

References