Cyber Resilience

CVE-2025-9303

Memory Safety in Totolink A720R Firmware 4.1.5cu.630_b20250509

Public PoCMemory Safety
Published
21 August 2025
Modified
17 June 2026
CVSS Score v4 7.4
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0084 54th percentile
Risk Priority 38 floored blend · peak EPSS

Summary

CVE-2025-9303 is a high-severity Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119) vulnerability in Totolink A720R Firmware. Its CVSS base score is 7.4 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 46% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

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

CVE-2025-9303 is a buffer overflow vulnerability (CWE-119, CWE-120) affecting the TOTOLINK A720R router on firmware version 4.1.5cu.630_B20250509. The issue exists in the setParentalRules function of the /cgi-bin/cstecgi.cgi component, where manipulation of the "desc" argument triggers the overflow.

Attackers with low privileges can exploit this remotely over the network (AV:N) with low attack complexity (AC:L), no user interaction required (UI:N), and unchanged scope (S:U), achieving high impacts on confidentiality, integrity, and availability (C:H/I:H/A:H), for an overall CVSS v3.1 score of 8.8. Exploitation enables potential remote code execution on the affected device.

Advisories reference a public proof-of-concept and exploit available on GitHub at repositories under lin-3-start/lin-cve for TOTOLINK A720R, along with VulDB entries detailing the issue (ctiid.320908, id.320908). No specific patches or mitigation steps are outlined in the provided references. The exploit has been publicly released, increasing the risk of active exploitation.

EU & UK References

Vulnerability Data

A security flaw has been discovered in TOTOLINK A720R 4.1.5cu.630_B20250509. This issue affects the function setParentalRules of the file /cgi-bin/cstecgi.cgi. Performing manipulation of the argument desc results in buffer overflow. The attack is possible to be carried out remotely. The…

more

exploit has been released to the public and may be exploited.

CWE(s)
CWE-119CWE-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 →
T1055 Process Injection Stealth
Adversaries may inject code into processes in order to evade process-based defenses as well as possibly elevate privileges.
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-2025-6128Same vendor: Totolink
CVE-2025-6147Same vendor: Totolink
CVE-2025-6165Same vendor: Totolink
CVE-2025-5737Same vendor: Totolink
CVE-2025-5789Same vendor: Totolink
CVE-2026-1157Same vendor: Totolink
CVE-2024-8573Same vendor: Totolink
CVE-2025-6568Same vendor: Totolink
CVE-2025-3989Same vendor: Totolink
CVE-2025-7837Same vendor: Totolink

Affected Assets

totolink
a720r firmware
4.1.5cu.630_b20250509

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)
  • V17.3.2
  • V5.2.1

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and analysis can find missing size checks before deployment.

SI-10 Information Input Validation good match

Input validation directly enforces size checks before buffer copies.

SA-8 Security and Privacy Engineering Principles partial match

Secure engineering principles require memory-safe design and coding that structurally avoids buffer-boundary violations.

SI-16 Memory Protection partial match

Memory protection restricts exploitation impact of buffer overflows without eliminating the underlying coding flaw.

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 SDLC practices (bounds checking, safe APIs, reviews) directly prevent this class of flaw.

ID.RA-01 partial match
prevents

Vulnerability scanning and code analysis directly surface buffer-boundary flaws.

ID.RA-08 partial match
prevents

Receiving and triaging vulnerability disclosures commonly includes buffer-related reports.

PR.AT-02 partial match
prevents

Developer training on secure coding reduces introduction of memory-buffer errors.

PR.PS-02 partial match
prevents

Patching replaces vulnerable code containing buffer-boundary defects.

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 catches out-of-bounds accesses before release, covering most instances of the weakness.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates memory-safety practices that directly prevent buffer-boundary violations.

A.8.26 Application security requirements partial match
prevents

Application security requirements can specify memory-safety rules, but do not prescribe implementation details.

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

Secure architecture and engineering principles include memory-safe design patterns that mitigate buffer overflows.

References