Cyber Resilience

CVE-2025-8136

HighPublic PoC

Published: 25 July 2025

Published
25 July 2025
Modified
28 July 2025
KEV Added
Patch
CVSS Score v4 7.4 CVSS: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 0.0143 81.1th percentile
Risk Priority 16 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2025-8136 is a high-severity Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119) vulnerability in Totolink A702R Firmware. Its CVSS base score is 7.4 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 18.9% 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 are NIST 800-53 SI-10 (Information Input Validation) and SI-16 (Memory Protection).

Deeper analysis

A critical buffer overflow vulnerability exists in the TOTOLINK A702R router running firmware 4.0.0-B20230721.1521. The flaw is located in an unknown function of the /boafrm/formFilter file within the HTTP POST Request Handler component. Manipulation of the ip6addr argument triggers the overflow, which is tracked under CWE-119 and CWE-120 and carries a CVSS 4.0 score of 7.4.

An authenticated attacker with network access can exploit the issue remotely to achieve high impact on confidentiality, integrity, and availability. The attack requires no user interaction and a publicly disclosed proof-of-concept is available, allowing an adversary to send a crafted HTTP POST request that overflows the buffer.

References point to a GitHub disclosure, multiple VulDB entries, and the vendor site, but contain no details on patches, firmware updates, or other mitigations. The associated EPSS score has remained low and essentially flat at 0.0143–0.0144.

EU & UK References

Vulnerability details

A vulnerability, which was classified as critical, was found in TOTOLINK A702R 4.0.0-B20230721.1521. Affected is an unknown function of the file /boafrm/formFilter of the component HTTP POST Request Handler. The manipulation of the argument ip6addr leads to buffer overflow. It…

more

is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

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.
T1499.004 Application or System Exploitation Impact
Adversaries may exploit software vulnerabilities that can cause an application or system to crash and deny availability to users.
Why these techniques?

Buffer overflow in public-facing router web interface (/boafrm/formFilter) enables remote exploitation (T1190) and application/system DoS via crafted HTTP POST with ip6addr (T1499.004). PoC demonstrates DoS; critical impact on CIA suggests potential for broader abuse.

CVEs Like This One

CVE-2025-8138Same product: Totolink A702R
CVE-2025-8137Same product: Totolink A702R
CVE-2025-8139Same product: Totolink A702R
CVE-2025-8140Same product: Totolink A702R
CVE-2025-9779Same product: Totolink A702R
CVE-2025-9782Same product: Totolink A702R
CVE-2025-9780Same product: Totolink A702R
CVE-2025-9783Same product: Totolink A702R
CVE-2025-9781Same product: Totolink A702R
CVE-2025-8246Same vendor: Totolink

Affected Assets

totolink
a702r firmware
4.0.0-b20230721.1521

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

prevent

SI-10 requires validation of inputs like the ip6addr argument in HTTP POST requests to prevent buffer overflows by ensuring proper length and format checks.

prevent

SI-16 implements memory protections such as stack canaries, ASLR, and DEP to mitigate exploitation of buffer overflows even if invalid input reaches the vulnerable function.

prevent

SI-2 mandates timely identification, reporting, and patching of flaws like this buffer overflow vulnerability in router firmware to eliminate the root cause.

References