CVE-2026-21551

Unisoc Modem Denial of Service via Improper Input Validation

Published Aug 3, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
In modem, there is a possible improper input validation. This could lead to remote denial of service with no additional execution privileges needed

Analysis

AI-generated

Technical impact

The vulnerability is a CWE‑20 Improper Input Validation flaw located in the modem firmware of Unisoc (Shanghai) Technologies Co., Ltd. devices. A malformed packet or data stream can trigger an error path that leads to a device reset or other disruption, resulting in a denial‑of‑service condition. The attacker gains no execution privileges, and the impact fully compromises the availability of the modem function.

Affected Systems

Affected systems are modem chipsets from Unisoc (Shanghai) Technologies Co., Ltd., specifically the T8100, T9100, T8200, and T8300 product families. No firmware version details are listed, so any build that incorporates the vulnerable modem logic may be susceptible.

Risk and Exploitability

The CVSS score of 7.5 indicates a high overall risk, and the EPSS score of less than 1% shows a very low but non‑zero likelihood of exploitation. The vulnerability is not cataloged in CISA KEV. Based on the description, it is inferred that the flaw can be triggered by remote network traffic directed at the modem’s control interfaces, and exposure depends on how those interfaces are exposed. An unauthenticated attacker may be able to cause repeated service interruptions without special privileges.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Update the modem firmware to the latest version released by Unisoc (Shanghai) Technologies Co., Ltd. which addresses the input‑validation issue.
  • If a firmware update is not yet available, isolate the device by restricting external access to its management interfaces using firewalls or network segmentation.
  • Monitor modem logs and network traffic for abnormal or repeated reset or error patterns that could indicate exploitation attempts.

Generated by OpenCVE AI on August 4, 2026 at 22:22 UTC.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Unisoc
Unisoc t8100
Unisoc t8200
Unisoc t8300
Unisoc t9100
Vendors & Products Unisoc
Unisoc t8100
Unisoc t8200
Unisoc t8300
Unisoc t9100
Type Values Removed Values Added
Title Unisoc Modem Denial of Service via Improper Input Validation
Type Values Removed Values Added
Weaknesses CWE-20
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description In modem, there is a possible improper input validation. This could lead to remote denial of service with no additional execution privileges needed
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses
  • CWE-20

    Improper Input Validation

Sources

Status
PUBLISHED
Assigner
Unisoc
Published
Updated
Aug 3, 2026, 2:20 PM
Reserved
Dec 31, 2025, 7:33 AM
Status
Deferred
Published
Aug 3, 2026, 8:17 AM
Modified
Oct 23, 2026, 10:10 PM