CriticalPublic exploit

OS Command Injection in ToToLink A3300R /cgi-bin/cstecgi.cgi stunServerAddr Parameter

IdentifiersCVE-2026-31181CWE-78· Improper Neutralization of Special…

CVE-2026-31181 is an OS command injection vulnerability in ToToLink A3300R firmware version v17.0.0cu.557_B20221024. The issue is present in requests handled by /cgi-bin/cstecgi.cgi, where the stunServerAddr parameter is insufficiently sanitized before being used in a context that permits shell command execution. A remote attacker can supply crafted input to stunServerAddr and cause arbitrary operating system commands to be executed on the device.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows remote arbitrary command execution on the affected router. Based on the provided CVSS v3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), the vulnerability can be exploited over the network with low complexity, requires no privileges and no user interaction, and can result in high impact to confidentiality, integrity, and availability. An attacker could fully compromise the device, access or alter configuration and traffic-handling behavior, and disrupt normal operation.

Mitigation

If you can’t patch tonight, do this now.

Restrict network access to the router management interface and specifically to /cgi-bin/cstecgi.cgi from untrusted networks. Disable remote administration if not required, place the management plane behind trusted internal networks only, and use firewall or ACL controls to limit who can reach the device. Monitor for suspicious requests involving the stunServerAddr parameter and isolate or replace affected devices where patching is not yet possible.

Remediation

Patch, then assume compromise.

Upgrade from the affected ToToLink A3300R firmware version v17.0.0cu.557_B20221024 to a vendor-fixed release if one is available. The vulnerable handling of the stunServerAddr parameter in /cgi-bin/cstecgi.cgi should be corrected by eliminating shell invocation for untrusted input or by implementing strict server-side allowlisting and safe parameter handling. If no patched firmware is currently available, the information is currently not available beyond avoiding use of the affected version.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

TotolinkA3300r Firmwareoperating_system

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

3 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

3 SOURCESView more in app

cvefeed high severityNews

Apr 23, 2026

CVE-2026-31181 - Totolink A3300R Command Injection Vulnerability

A command injection vulnerability in ToToLink A3300R firmware v17.0.0cu.557_B20221024 that allows arbitrary command execution via the stunServerAddr parameter to /cgi-bin/cstecgi.cgi.

What this page doesn’t show

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Exposure mapping

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Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity2