Cve-2026-90689 - CraftedSignal Threat Feedhttps://feed.craftedsignal.io/tags/cve-2026-90689/Trending threats, MITRE ATT&CK coverage, and detection metadata. Fed continuously.Hugoenhello@craftedsignal.iohello@craftedsignal.ioMon, 14 Sep 2026 07:31:09 +0000https://feed.craftedsignal.io/favicon-32x32.pngCraftedSignal Threat Feedhttps://feed.craftedsignal.io/3232https://feed.craftedsignal.io/favicon.svgRemote Stack-Based Buffer Overflow in Tenda W20Ehttps://feed.craftedsignal.io/briefs/2026-09-tenda-w20e-overflow/Mon, 14 Sep 2026 07:31:09 +0000hello@craftedsignal.iohttps://feed.craftedsignal.io/briefs/2026-09-tenda-w20e-overflow/A stack-based buffer overflow in the Tenda W20E formDelWebAuthWhiteUser function allows remote unauthenticated attackers to execute arbitrary code or cause a denial of service via manipulation of the webAuthWhiteUserIndex argument.A critical security vulnerability has been identified in Tenda W20E firmware version 15.11.0.61068_1546_841_CN_TDC. The flaw resides within the formDelWebAuthWhiteUser function, which processes the webAuthWhiteUserIndex argument without sufficient bounds checking. This oversight introduces a stack-based buffer overflow condition. Because the vulnerable function is reachable via remote HTTP requests, an unauthenticated attacker can exploit this flaw to crash the device, resulting in a denial of service, or potentially achieve remote code execution (RCE) by overwriting stack memory. This vulnerability poses a significant risk to network infrastructure, as the Tenda W20E is typically deployed as a gateway or router. Organizations using this device should restrict access to the web management interface to trusted IP ranges and monitor for unusual traffic patterns targeted at administrative URI paths.

Attack Chain

  1. The attacker performs reconnaissance to identify Tenda W20E devices exposed to the internet.
  2. The attacker identifies the target URI or endpoint associated with the web authentication white user management functionality.
  3. The attacker crafts a malicious HTTP request containing a specially crafted value for the webAuthWhiteUserIndex parameter.
  4. The request is transmitted to the device's web management interface.
  5. The device's formDelWebAuthWhiteUser function parses the malicious input.
  6. The lack of bounds checking results in a memory corruption event on the device stack.
  7. Depending on the payload, the device either crashes (Denial of Service) or redirects the instruction pointer to attacker-controlled shellcode (Remote Code Execution).

Impact

Successful exploitation of CVE-2026-90689 allows an unauthenticated remote attacker to compromise the integrity and availability of Tenda W20E hardware. If used for code execution, the attacker could gain persistent control over the network gateway, enabling traffic interception, lateral movement, or further exploitation of connected internal systems.

Recommendation

  1. Restrict access to the Tenda W20E web management interface to known, trusted administrative IP addresses via firewall rules to block remote exploitation attempts.
  2. Monitor web server logs for anomalous POST requests to URI endpoints associated with white user management containing abnormally long or suspicious string patterns in the webAuthWhiteUserIndex parameter.
  3. Engage Tenda support or check for firmware updates addressing CVE-2026-90689; apply all relevant patches immediately upon availability.
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