What is the CVSS score of CVE-2025-71256?

CVE-2025-71256 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 0.1%.

Which versions of Unisoc T-series chipsets are affected by CVE-2025-71256?

CVE-2025-71256 is a remote denial-of-service vulnerability affecting Unisoc T8100/T9100/T8200/T8300 chipsets used in mobile devices, allowing unauthenticated attackers to disable 5G cellular…

How to fix or mitigate CVE-2025-71256?

24 hours: Identify and inventory all mobile devices in corporate environment using Unisoc T8100/T9100/T8200/T8300 chipsets (contact device manufacturers for compatibility lists). 7 days: Implement network segmentation to restrict 5G modem access where feasible; escalate to Unisoc and device OEM vendors for patch timeline and interim mitigation guidance; disable 5G connectivity on affected devices if operationally acceptable pending patch availability. 30 days: Maintain vendor contact for patch release notifications; evaluate device replacement timelines if critical mobile assets are affected; implement enhanced network monitoring for anomalous 5G modem behavior as compensating control.

Unisoc T-series chipsets CVE-2025-71256

EUVD-2025-209657 HIGH

2026-05-06 Unisoc

GHSA-9x33-p28p-x395

Denial Of Service T8100 T9100 T8200 T8300

7.5

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

7.5 HIGH

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

Analysis Generated

May 06, 2026 - 02:16 vuln.today

DescriptionCVE.org

In nr modem, there is a possible improper input validation. This could lead to remote denial of service with no additional execution privileges needed.

AnalysisAI

Remote denial of service in Unisoc T8100/T9100/T8200/T8300 chipset NR modem implementations allows unauthenticated network attackers to crash device cellular connectivity via malformed protocol input. The improper input validation in the 5G New Radio modem stack enables trivial remote service disruption requiring no user interaction or authentication. EPSS data not available; no evidence of active exploitation (not in CISA KEV). Affects mobile devices using these specific Unisoc chipset models in 5G NR mode.

Technical ContextAI

The vulnerability resides in the NR (New Radio) modem component of Unisoc's T-series chipsets (T8100, T9100, T8200, T8300). New Radio is the 3GPP 5G air interface standard for cellular communications. The modem firmware responsible for processing 5G protocol messages lacks proper input validation, allowing malformed network packets to trigger a denial of service condition. Unisoc is a Chinese fabless semiconductor company producing mobile chipsets widely used in budget and mid-range smartphones, particularly in Asian and emerging markets. The affected T-series are 5G-capable SoCs targeting smartphone implementations. Without CWE classification, the root cause class is unspecified, but the description points to classic input validation failures (likely related to CWE-20 Improper Input Validation or CWE-129 Improper Validation of Array Index). The network-facing nature and modem baseband context suggest protocol parsing vulnerabilities in RRC, NAS, or MAC layer message handlers.

RemediationAI

Apply firmware security updates from Unisoc addressing CVE-2025-71256 as detailed in their product security bulletin at https://www.unisoc.com/en/support/product-security-bulletin/2051836844671422466. Device manufacturers (OEMs) must integrate these chipset firmware patches and distribute them through standard Android/device security update channels-end users should check for and install device firmware updates from their manufacturer. The Unisoc advisory does not specify exact patched firmware versions in the available data, so consult the full bulletin for build numbers. As interim mitigation if patches are unavailable: (1) Disable 5G NR connectivity and force devices to 4G LTE mode if business requirements allow, eliminating the vulnerable NR modem attack surface (trade-off: reduced network performance and feature availability). (2) In enterprise environments with managed devices, restrict deployment of affected Unisoc chipset models in high-security contexts until patches are verified. (3) Implement network-level monitoring for anomalous cellular connectivity patterns that may indicate DoS attempts. Note that compensating controls are limited because the vulnerability exists in closed-source modem baseband firmware-application-layer or OS-level mitigations cannot address the root cause, and disabling 5G negates the primary value proposition of these chipsets.