CVE-2026-2870Public exploitNetwork attack vector

Remote code execution via unbounded QoS list copy

Published Feb 21, 2026 · Updated Feb 21, 2026

Stack-based buffer overflow in Tenda A21 1.0.0.0 allows remote authenticated users to execute code via a crafted QoS list. The set_qosMib_list function copies the user-controlled list parameter with strcpy into the 256-byte qos_str stack buffer without checking its length. Low-privileged access to the web management interface is required; oversized input can overwrite the return address, execute code, or crash httpd.

CVSS severity8.8
High
EPSS probability0.59%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in Tenda A21 1.0.0.0 allows remote authenticated users to execute code via a crafted QoS list. The set_qosMib_list function copies the user-controlled list parameter with strcpy into the 256-byte qos_str stack buffer without checking its length. Low-privileged access to the web management interface is required; oversized input can overwrite the return address, execute code, or crash httpd.

The record

CVE
CVE-2026-2870
Published
Feb 21, 2026
Updated
Feb 21, 2026
Vendor
Shenzhen Tenda Technology Co., Ltd.
Product
A21
Classifications
CWE-119, CWE-121, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.0.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Shenzhen Tenda Technology Co., Ltd. · A21version=1.0.0.0

Published CVSS scores

8.8VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
9.0VulDBAV:N/AC:L/Au:S/C:C/I:C/A:C
7.4VulDBCVSS: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

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-121Stack-based Buffer Overflow
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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