CVE-2024-2891 Overview
CVE-2024-2891 is a stack-based buffer overflow in the Tenda AC7 router firmware version 15.03.06.44. The flaw resides in the formQuickIndex function handling requests to /goform/QuickIndex. Attackers can trigger the overflow by manipulating the PPPOEPassword argument. The vulnerability is remotely exploitable and has been publicly disclosed with proof-of-concept details available on GitHub. The identifier VDB-257934 was assigned to this issue. According to the disclosure, the vendor was contacted but did not respond. The weakness is tracked under [CWE-121] (Stack-based Buffer Overflow) and [CWE-787] (Out-of-bounds Write).
Critical Impact
Remote attackers with low-privilege access can corrupt stack memory on affected Tenda AC7 devices, potentially leading to arbitrary code execution and full device compromise.
Affected Products
- Tenda AC7 router (hardware)
- Tenda AC7 firmware version 15.03.06.44
- Devices exposing the /goform/QuickIndex web management endpoint
Discovery Timeline
- 2024-03-26 - CVE-2024-2891 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2024-2891
Vulnerability Analysis
The vulnerability affects the formQuickIndex handler in the web management interface of the Tenda AC7 router. This function processes configuration requests submitted to the /goform/QuickIndex endpoint, including PPPoE authentication parameters. The PPPOEPassword argument is copied into a fixed-size stack buffer without adequate length validation. Supplying an oversized value overflows the buffer and overwrites adjacent stack data, including saved return addresses on the MIPS-based device. An attacker with network reachability to the router's HTTP interface can send a crafted POST request to trigger the condition. Successful exploitation typically results in denial of service and, on embedded targets like this one, can be extended to arbitrary code execution given the absence of modern exploit mitigations on many consumer routers.
Root Cause
The root cause is missing bounds checking on user-controlled input during string copy operations inside formQuickIndex. The handler trusts the length of PPPOEPassword and writes it into a stack-allocated buffer, violating [CWE-121] and [CWE-787]. Consumer-grade router firmware often lacks stack canaries, ASLR, and non-executable stack protections, which increases the exploitability of such overflows.
Attack Vector
Exploitation requires network access to the router's administrative HTTP interface and low-privilege authenticated context. An attacker sends a POST request to /goform/QuickIndex with an oversized PPPOEPassword parameter. The malformed request corrupts the stack frame of formQuickIndex, enabling control-flow hijacking. Public proof-of-concept details describing the request structure and offset are documented in the GitHub IoT-vulnerable repository.
No verified exploit code is reproduced here. For technical specifics on the crash offset and payload construction, refer to the public VulDB entry #257934 and the linked proof-of-concept.
Detection Methods for CVE-2024-2891
Indicators of Compromise
- HTTP POST requests to /goform/QuickIndex containing abnormally long PPPOEPassword values (typically exceeding a few hundred bytes)
- Unexpected reboots, crashes, or httpd process restarts on Tenda AC7 devices
- Configuration changes or new administrative sessions following anomalous requests to the router management interface
- Outbound connections from the router to unknown hosts, indicative of post-exploitation implant activity
Detection Strategies
- Inspect web server and router logs for repeated requests to /goform/QuickIndex with parameter lengths outside normal ranges
- Deploy network intrusion detection signatures that flag POST /goform/QuickIndex traffic containing oversized form fields
- Baseline administrative HTTP traffic to consumer routers and alert on volume or payload anomalies
Monitoring Recommendations
- Restrict management-plane traffic to a dedicated VLAN and monitor for lateral access attempts from user segments
- Aggregate router syslog output into a centralized logging pipeline to observe crash patterns and authentication anomalies
- Track firmware versions across deployed Tenda devices to identify unpatched 15.03.06.44 units exposed to internal or external networks
How to Mitigate CVE-2024-2891
Immediate Actions Required
- Disable remote (WAN-side) access to the Tenda AC7 web management interface
- Restrict LAN-side administrative access to trusted management hosts only
- Rotate router administrator credentials and PPPoE credentials to reduce the value of low-privilege footholds
- Segment vulnerable Tenda AC7 devices away from sensitive network zones until a firmware fix is available
Patch Information
No vendor patch has been published for CVE-2024-2891 as of the last NVD update on 2026-06-17. The disclosure notes that Tenda was contacted but did not respond. Operators should monitor the Tenda support portal for firmware updates superseding version 15.03.06.44 and apply them promptly when released.
Workarounds
- Replace affected Tenda AC7 units with supported hardware from vendors that provide active firmware maintenance
- Place the router behind an upstream firewall that blocks unsolicited access to TCP ports used by the management interface
- Enforce strong, unique administrative credentials to raise the bar for the authenticated attack precondition
- Disable the PPPoE quick-setup workflow if the deployment does not require it
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
