What is the CVSS score of CVE-2025-7421?

CVE-2025-7421 has a CVSS 3.1 base score of 8.8 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.4%.

Which versions of O3 Firmware are affected by CVE-2025-7421?

A critical remote code execution vulnerability affects Tenda O3V2 routers (version 1.0.0.12) with no vendor patch currently available.

Is there a public PoC exploit available for CVE-2025-7421?

Yes, a public proof-of-concept exploit is available for CVE-2025-7421. Prioritise patching immediately. EPSS: 0.4%.

How to fix or mitigate CVE-2025-7421?

Within 24 hours: Identify and inventory all Tenda O3V2 1.0.0.12(3880) devices in your environment; isolate affected devices from critical systems if possible. Within 7 days: Implement network segmentation to restrict access to the vulnerable httpd service; deploy WAF rules to block malicious MAC filter requests if internet-exposed; monitor for exploitation attempts. Within 30 days: Replace vulnerable Tenda devices with patched/alternative vendors; if replacement unavailable, maintain strict network access controls and continuous monitoring until vendor patch is released.

O3 Firmware CVE-2025-7421

EUVD-2025-21090 HIGH

Buffer Overflow (CWE-119)

2025-07-11 cna@vuldb.com

Buffer Overflow O3 Firmware Tenda

8.8

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

8.8 HIGH

AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

EUVD ID Assigned

Mar 16, 2026 - 08:17 euvd

EUVD-2025-21090

Analysis Generated

Mar 16, 2026 - 08:17 vuln.today

PoC Detected

Jul 16, 2025 - 16:43 vuln.today

Public exploit code

CVE Published

Jul 11, 2025 - 01:15 nvd

HIGH 8.8

DescriptionCVE.org

A vulnerability was found in Tenda O3V2 1.0.0.12(3880). It has been rated as critical. This issue affects the function fromMacFilterModify of the file /goform/operateMacFilter of the component httpd. The manipulation of the argument mac leads to stack-based buffer overflow. The attack may be initiated remotely. The exploit has been disclosed to the public and may be used.

AnalysisAI

A critical stack-based buffer overflow vulnerability exists in Tenda O3V2 firmware version 1.0.0.12(3880) in the MAC filter modification function. An authenticated remote attacker can exploit improper input validation of the 'mac' parameter to achieve remote code execution with full system compromise (confidentiality, integrity, and availability impact). The vulnerability has public exploit disclosure and demonstrates high real-world exploitability.

Technical ContextAI

The vulnerability resides in the httpd web server component of Tenda O3V2 router firmware, specifically in the fromMacFilterModify function handling requests to /goform/operateMacFilter. The root cause is CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), manifesting as a classic stack-based buffer overflow. The mac parameter undergoes insufficient bounds checking before being written to a stack-allocated buffer, allowing an attacker to overflow the buffer and overwrite the stack frame, including return addresses and saved registers. This is a memory safety issue common in C/C++ firmware implementations lacking modern protections. The affected product is a wireless mesh router system where httpd processes user requests, making this directly network-accessible after authentication.

RemediationAI

Contact Tenda support or check their official website for firmware updates beyond version 1.0.0.12(3880). Firmware updates should include bounds checking fixes in the fromMacFilterModify function.; priority: Critical - Apply immediately Workaround: Restrict access to the router's web interface (httpd) to trusted networks only. Disable remote management if enabled. Use a firewall rule to block external access to the management interface (typically port 80/443).; priority: Temporary mitigation pending patch Detection: Monitor httpd logs for unusual requests to /goform/operateMacFilter endpoint, especially those with oversized or malformed 'mac' parameter values. Look for stack traces or unexpected service crashes.; priority: Ongoing Access Control: Enforce strong authentication credentials on router admin accounts and disable default credentials. Limit which devices/users can authenticate to the router.; priority: High