Is CVE-2026-123966 being exploited in the wild?

At the time of the last update, CVE-2026-123966 was not in the CISA Known Exploited Vulnerabilities catalog. Recheck the catalog regularly.

How do I fix CVE-2026-123966?

Upgrade Tenda AC19 to the fixed version named in the vendor advisory listed under Technical References. If you cannot patch right away, limit network access to the affected component and monitor it closely until you can.

How serious is CVE-2026-123966?

It is rated critical with a CVSS base score of 9.3. The flaw can be reached over the network, needs no login, and needs no user interaction. In CTEM terms, combine that with how exposed and important the affected system is to set the real priority.

CVE-2026-123966: Tenda AC19 Memory Buffer Errors Vulnerability

CVSS

9.3 CRITICAL

EPSS

n/a

CISA KEV

Not listed

CWE

CWE-119

Sources: National Vulnerability Database, CVE.org, CISA KEV, FIRST EPSS

CVE-2026-123966 Overview

A vulnerability was determined in Tenda AC19 16.03.10.07. Affected by this issue is the function saveParentControlInfo of the file /goform/saveParentControlInfo. This manipulation of the argument deviceId causes heap-based buffer overflow. The attack is possible to be carried out remotely. The exploit has been publicly disclosed and may be utilized.

Critical Impact

Remote, unauthenticated attackers can exploit this Memory Buffer Errors in Tenda AC19. The CVSS base score is 9.3 (Critical).

Affected Products

Tenda AC19: see the vendor advisory for the exact affected versions

Discovery Timeline

2026-11-07: CVE-2026-123966 published to the National Vulnerability Database by cna@vuldb.com
2026-11-07: last updated in the NVD database

Technical Details for CVE-2026-123966

Vulnerability Analysis

CVE-2026-123966 is a Memory Buffer Errors weakness (CWE-119: Memory Buffer Errors, CWE-122: Heap Buffer Overflow) in Tenda AC19. Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. The program reads or writes outside the memory it should.

With a CVSS base score of 9.3, apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Root Cause

The weakness is classified as CWE-119: Memory Buffer Errors, CWE-122: Heap Buffer Overflow. The program reads or writes outside the memory it should.

Attack Vector

Based on the CVSS vector, the flaw can be reached over the network, needs no login, 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:N/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-2026-123966

Detection Strategies

Inventory every instance of Tenda AC19 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 AC19 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-2026-123966

Immediate Actions Required

Apply the fixed version of Tenda AC19 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 AC19.

Advisory on tenda.com.cn

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

CWE-119: Memory Buffer Errors More CVEs with this weakness
CWE-122: Heap Buffer Overflow More CVEs with this weakness

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

CVE-2026-123966 is a critical severity Memory Buffer Errors in Tenda AC19 with a CVSS score of 9.3. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

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Mar 24, 2026

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