Quick answer
Direct answer
Risk scores
| CVSS metric | What it means |
|---|---|
| Attack vector (AV:N) | Network: reachable remotely |
| Attack complexity (AC:L) | Low complexity |
| Privileges required (PR:L) | Low privileges required |
| User interaction (UI:N) | No user interaction |
| Scope (S:U) | Scope unchanged |
| Confidentiality (C:H) | High confidentiality impact |
| Integrity (I:H) | High integrity impact |
| Availability (A:H) | High availability impact |
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
About Totolink A3002ru Firmware
CVE-2026-26731 affects Totolink A3002ru Firmware, a product from Totolink. Before acting, confirm where Totolink A3002ru Firmware runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.
What the flaw is
In plain terms: TOTOLINK A3002RU V2.1.1-B20211108.1455 was discovered to contain a stack-based buffer overflow via the routernamer`parameter in the formDnsv6 function.
The weakness class is Out of Bounds Write. The program writes past the end of a buffer, a common path to code execution.
Based on its CVSS vector, the flaw can be reached over the network, needs some level of access, and needs no user interaction. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Affected versions and timeline
| Field | Detail |
|---|---|
| Product | Totolink A3002ru Firmware |
| Affected versions | A3002ru Firmware 2.1.1-b20211108.1455 |
| Published | Feb 17, 2026 |
| Last modified | Sep 21, 2026 |
| Added to CISA KEV | Not listed |
| Assigning CNA | cve@mitre.org |
How to detect it
- Inventory every instance of Totolink A3002ru Firmware and record the running version against the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
- Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.
How to fix it
- Apply the fixed version of Totolink A3002ru Firmware named in the vendor advisory.
- If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
- Rescan after the change to prove the exposure is gone, then close the ticket.
CTEM action plan
| CTEM stage | What to do for this CVE |
|---|---|
| Scope | Add every business service that depends on Totolink A3002ru Firmware to the current CTEM cycle. |
| Discover | Find all instances, including shadow and cloud deployments, and record versions and exposure. |
| Prioritize | Rank using EPSS and CVSS together with asset exposure and business impact. |
| Validate | Confirm the flaw is reachable and exploitable in your environment and that compensating controls work. |
| Mobilize | Assign the fix to the asset owner with a due date matched to the priority, then verify closure. |
CWE References
- CWE-787: Out of Bounds Write More CVEs with this weakness
- CWE-121: Stack Buffer Overflow More CVEs with this weakness
Technical References
Frequently asked questions
Related CVEs
A flaw has been found in TOTOLINK X6000R 9.4.0cu.1360_B20241207/9.4.0cu.1498_B20250826. Affected by this issue is the function setLanCfg of the file /usr/sbin/shttpd. Executing a manipulation of the argument Hostname can lead to os command injection. The attack may be launched remotely.
TOTOLINK X5000R V9.1.0cu.2415_B20250515 contains a denial-of-service vulnerability in /cgi-bin/cstecgi.cgi. The CGI reads the CONTENT_LENGTH environment variable and allocates memory using malloc (CONTENT_LENGTH + 1) without sufficient bounds checking. When lighttpd s request size limit is not enforced, a crafted large POST request can cause memory exhaustion or a segmentation fault, leading to a crash of the management CGI and loss of availability of the web interface.
TOTOLINK X6000R v9.4.0cu.1498_B20250826 contains an OS command injection vulnerability in the NTPSyncWithHost handler of the /usr/sbin/shttpd executable. The host_time parameter is retrieved via sub_40C404 and passed to a date -s shell command through CsteSystem. While the first two tokens of the input are validated, the remainder of the string is not sanitized, allowing authenticated attackers to execute arbitrary shell commands via shell metacharacters.
TOTOLINK X5000R v9.1.0cu_2415_B20250515 contains an argument injection vulnerability in the setDiagnosisCfg handler of the /usr/sbin/lighttpd executable. The ip parameter is retrieved via websGetVar and passed to a ping command through CsteSystem without validating if the input starts with a hyphen (-). This allows remote authenticated attackers to inject arbitrary command-line options into the ping utility, potentially leading to a Denial of Service (DoS) by causing excessive resource consumption or prolonged execution.
TOTOLINK A3002RU_V3 V3.0.0-B20220304.1804 was discovered to contain a stack-based buffer overflow via the static_ipv6 parameter in the formIpv6Setup function.
TOTOLINK A3002RU V2.1.1-B20211108.1455 was discovered to contain a stack-based buffer overflow via the vpnUser or vpnPassword` parameters in the formFilter function.
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