Cyber Resilience

CVE-2025-9533

Medium

Published: 27 August 2025

Published
27 August 2025
Modified
29 April 2026
KEV Added
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Patch
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CVSS Score v4 5.5 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/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 0.0031 54.3th percentile
Risk Priority 11 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2025-9533 is a medium-severity Improper Authentication (CWE-287) vulnerability in Totolink T10 Firmware. Its CVSS base score is 5.5 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 45.7% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified are NIST 800-53 AC-3 (Access Enforcement) and AC-17 (Remote Access).

Deeper analysis

CVE-2025-9533 is an improper authentication vulnerability (CWE-287) in the TOTOLINK T10 router firmware version 4.1.8cu.5241_B20210927. The flaw affects an unknown function in the /formLoginAuth.htm file, where manipulation of the authCode parameter using the input "1" bypasses authentication mechanisms.

A remote, unauthenticated attacker can exploit this vulnerability with low attack complexity and no user interaction required, as reflected in its CVSS v3.1 base score of 7.3 (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L). Successful exploitation allows the attacker to gain unauthorized access to the device, resulting in low-level impacts to confidentiality, integrity, and availability.

Advisories and related resources, including a public proof-of-concept exploit on GitHub at https://github.com/aLtEr6/MY_test/blob/main/TOTOLINK/TOTOLINK%20T10%20Vulnerability.md and VulDB entries at https://vuldb.com/?ctiid.321552, https://vuldb.com/?id.321552, and https://vuldb.com/?submit.635941, detail the issue. The TOTOLINK vendor website at https://www.totolink.net/ should be consulted for any firmware updates or mitigation guidance.

EU & UK References

Vulnerability details

A vulnerability has been found in TOTOLINK T10 4.1.8cu.5241_B20210927. Affected is an unknown function of the file /formLoginAuth.htm. The manipulation of the argument authCode with the input 1 leads to improper authentication. The attack can be initiated remotely. The exploit…

more

has been disclosed to the public and may be used.

CWE(s)
CWE-287

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.
attack.mitre.org →
Why these techniques?

Direct improper authentication bypass on the router's public web interface (/formLoginAuth.htm) enables remote exploitation of a public-facing application for initial unauthorized access.

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

CVEs Like This One

CVE-2025-14964Same product: Totolink T10
CVE-2025-44655Same product: Totolink T10
CVE-2025-12259Same vendor: Totolink
CVE-2025-12239Same vendor: Totolink
CVE-2026-1328Same vendor: Totolink
CVE-2026-1156Same vendor: Totolink
CVE-2025-7837Same vendor: Totolink
CVE-2026-26736Same vendor: Totolink
CVE-2025-12241Same vendor: Totolink
CVE-2025-25609Same vendor: Totolink

Affected Assets

totolink
t10 firmware
4.1.8cu.5241_b20210927

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

AC-3 Access Enforcement good match
prevent

Directly enforces authentication decisions on /formLoginAuth.htm so that manipulation of authCode cannot bypass login.

AC-17 Remote Access partial match
prevent

Requires cryptographic or strong authentication for all remote management sessions to the router's web interface.

IA-8 Identification and Authentication (Non-organizational Users) partial match
prevent

Mandates identification and authentication of non-organizational users before any access is granted to device functions.

References