Cyber Resilience

CVE-2023-39747

Memory Safety in Tp-Link Tl-Wr940N V2 Firmware

Public PoCMemory Safety
Published
21 August 2023
Modified
21 November 2024
CVSS Score v3.1 9.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.078 94th percentile
Risk Priority 81 floored blend · peak EPSS

Summary

CVE-2023-39747 is a critical-severity Classic Buffer Overflow (CWE-120) vulnerability in Tp-Link Tl-Wr940N V2 Firmware. Its CVSS base score is 9.8 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 6% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

TP-Link WR841N V8, TL-WR940N V2, and TL-WR941ND V5 routers contain a stack-based buffer overflow vulnerability (CWE-120) triggered by the radiusSecret parameter in the /userRpm/WlanSecurityRpm endpoint. The flaw received a CVSS 3.1 score of 9.8, reflecting network-accessible input handling without authentication or user interaction.

An unauthenticated remote attacker can supply a crafted radiusSecret value to overflow the buffer, resulting in arbitrary code execution with full control over the device confidentiality, integrity, and availability. The attack requires only a single HTTP request to the management interface and succeeds against the listed firmware versions.

Public references consist of technical write-ups hosted on GitHub that document the parameter handling and reproduction steps; no vendor advisory, firmware patch, or mitigation guidance is referenced in the available sources. The associated EPSS score has remained flat at 0.1254 with no material increase since disclosure.

EU & UK References

Vulnerability Data

TP-Link WR841N V8, TP-Link TL-WR940N V2, and TL-WR941ND V5 were discovered to contain a buffer overflow via the radiusSecret parameter at /userRpm/WlanSecurityRpm.

CWE(s)
CWE-120

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 →
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-2023-39745Same product: Tp-Link Tl-Wr841N V8
CVE-2025-25900Same vendor: Tp-Link
CVE-2026-15314Same vendor: Tp-Link
CVE-2024-54887Same vendor: Tp-Link
CVE-2024-48712Same vendor: Tp-Link
CVE-2023-30383Same vendor: Tp-Link
CVE-2023-36354Same vendor: Tp-Link
CVE-2026-34124Same vendor: Tp-Link
CVE-2023-36359Same vendor: Tp-Link
CVE-2023-34832Same vendor: Tp-Link

Affected Assets

tp-link
tl-wr940n v2 firmware
all versions
tp-link
tl-wr941nd v5 firmware
all versions
tp-link
tl-wr841n v8 firmware
all versions

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V5.2.1

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.

SC-27 Platform-independent Applications
addresses: CWE-120

Platform-independent managed code eliminates the need for unchecked native buffer copies that are the root cause of classic buffer overflows.

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 directly enforce bounds checking and input validation that prevent classic buffer overflows.

ID.RA-01 partial match
prevents

Vulnerability identification processes such as code review or scanning detect classic buffer overflows before exploitation.

PR.PS-02 partial match
prevents

Routine patching replaces vulnerable code containing unchecked buffer copies with corrected versions.

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.8.28 Secure coding mostly match
prevents

Secure coding directly requires bounds-checked memory operations, addressing the root cause of CWE-120.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development and acceptance can detect buffer overflows through fuzzing and static analysis, though it does not prevent them at the source.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates processes that can include input validation and bounds checking to prevent buffer overflows.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify input-size validation and safe buffer handling to mitigate classic buffer overflows.

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

Secure system architecture and engineering principles promote defensive coding patterns that reduce the likelihood of unchecked buffer copies.

References