CVE-2026-2191
Published: 08 February 2026
Summary
CVE-2026-2191 is a high-severity Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119) vulnerability in Tenda Ac9 Firmware. Its CVSS base score is 7.3 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 40.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and AC-6 (Least Privilege).
Deeper analysis
CVE-2026-2191 is a stack-based buffer overflow vulnerability affecting the Tenda AC9 router on firmware version 15.03.06.42_multi. The flaw resides in the formGetDdosDefenceList function, where manipulation of the security.ddos.map argument triggers the overflow. It is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-121 (Stack-based Buffer Overflow).
The vulnerability carries a CVSS v3.1 base score of 7.2 (AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H), indicating network-based exploitation with low attack complexity, no user interaction required, but high privileges (such as administrative access) needed. An attacker with sufficient privileges can remotely initiate the exploit to achieve high impacts on confidentiality, integrity, and availability, potentially leading to full device compromise.
Advisories reference a public exploit in a GitHub repository (https://github.com/glkfc/IoT-Vulnerability/blob/main/Tenda/tenda3.md) and multiple VulDB entries (https://vuldb.com/?ctiid.344894, https://vuldb.com/?id.344894, https://vuldb.com/?submit.749800), noting that the exploit is available for attacks. The Tenda vendor site (https://www.tenda.com.cn/) should be consulted for any patches or mitigation guidance.
The exploit has been made publicly available, increasing the risk of real-world attacks against vulnerable Tenda AC9 devices.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-6446
Vulnerability details
A weakness has been identified in Tenda AC9 15.03.06.42_multi. Affected is the function formGetDdosDefenceList. This manipulation of the argument security.ddos.map causes stack-based buffer overflow. The attack may be initiated remotely. The exploit has been made available to the public and…
more
could be used for attacks.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Authenticated RCE via buffer overflow in public-facing router web interface directly maps to exploitation of a network-accessible application.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Enforces validation of the security.ddos.map argument in formGetDdosDefenceList to block the stack-based buffer overflow.
Applies memory protection mechanisms that can prevent successful exploitation of the stack overflow despite the coding flaw.
Limits administrative privileges required for remote access to the vulnerable function, reducing the pool of potential attackers.