Sources: National Vulnerability Database, CVE.org, CISA KEV, FIRST EPSS
CVE-2026-129258 Overview
A vulnerability was identified in Tenda AC18 15.03.05.05_multi/15.03.05.19 Build 6318. Affected by this vulnerability is an unknown functionality of the file /cgi-bin/upgrade of the component Firmware Upgrade Handler. Such manipulation of the argument upgradeFile leads to insufficient verification of data authenticity. The attack may be launched remotely. The exploit is publicly available and might be used.
Critical Impact
Affected Products
- Tenda AC18: see the vendor advisory for the exact affected versions
Discovery Timeline
- 2026-11-14: CVE-2026-129258 published to the National Vulnerability Database by cna@vuldb.com
- 2026-11-14: last updated in the NVD database
Technical Details for CVE-2026-129258
Vulnerability Analysis
CVE-2026-129258 is a Security Vulnerability weakness (CWE-345) in Tenda AC18. Based on its CVSS vector, the flaw can be reached over the network, needs some level of access, and needs no user interaction.
With a CVSS base score of 8.5, apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Root Cause
The vendor description states: A vulnerability was identified in Tenda AC18 15.03.05.05_multi/15.03.05.19 Build 6318. Affected by this vulnerability is an unknown functionality of the file /cgi-bin/upgrade of the component Firmware Upgrade Handler. Such manipulation of the argument upgradeFile leads to insufficient verification of data authenticity. The attack may be launched remotely. The exploit is publicly available and might be used.
Attack Vector
Based on the CVSS vector, the flaw can be reached over the network, needs some level of access, and needs no user interaction. Attack complexity is low complexity.
No exploitation in the wild is confirmed by CISA at the time of the last update. Check the references below for any vendor or researcher proof of concept.
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Detection Methods for CVE-2026-129258
Detection Strategies
- Inventory every instance of Tenda AC18 and compare the running version with the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Run an authenticated vulnerability scan once your scanner ships a check for this CVE.
Monitoring Recommendations
- Forward Tenda AC18 application, access and audit logs to your SIEM for retrospective hunting.
- Alert on new processes, configuration changes or outbound connections from the affected service.
- Track the vendor advisory and the CISA KEV catalog for changes in exploitation status.
How to Mitigate CVE-2026-129258
Immediate Actions Required
- Apply the fixed version of Tenda AC18 named in the vendor advisory.
- Prioritize internet facing and business critical instances first.
- Rescan after the change to confirm the exposure is closed.
Patch Information
Use the fixed version listed in the vendor advisory for Tenda AC18.
Workarounds
- If patching must wait, restrict network access to the affected service and place it behind authentication or a web application firewall rule.
CWE References
Technical References
This entry is built directly from NVD, CISA KEV and EPSS data. Verify fixed versions in the vendor advisory before you deploy.
Frequently asked questions
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