TL-WR940N v6: Stack-based Buffer Overflow
CVE-2026-12935 is a high-severity stack-based buffer overflow vulnerability in TL-WR940N v6 from TP-Link, with a CVSS 4.0 base score of 8.7 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists versions (US)_V6_260528, (JP)_V6_260527, (EU)_V6_260528 as the first without the flaw, so updating TL-WR940N v6 to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.99% chance of exploitation within 30 days, higher than 63% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update TL-WR940N v6 to (US)_V6_260528 or (JP)_V6_260527 or (EU)_V6_260528, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| TP-Link | TL-WR940N v6 | before (US)_V6_260528; before (JP)_V6_260527; before (EU)_V6_260528 | (US)_V6_260528, (JP)_V6_260527, (EU)_V6_260528 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Attack requirements
- NoneThe attack does not depend on a particular deployment or configuration.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- PassiveA user only needs to do something routine, such as viewing a page.
- Confidentiality (vulnerable system)
- HighSerious loss of confidentiality on the vulnerable system.
- Integrity (vulnerable system)
- HighSerious loss of integrity on the vulnerable system.
- Availability (vulnerable system)
- HighSerious loss of availability on the vulnerable system.
- Confidentiality (other systems)
- NoneNo loss of confidentiality on systems beyond the vulnerable one.
- Integrity (other systems)
- NoneNo loss of integrity on systems beyond the vulnerable one.
- Availability (other systems)
- NoneNo loss of availability on systems beyond the vulnerable one.
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/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. Scored by CNA.
Official description
The TL-WR940N v6 router contains a vulnerability in its RTSP connection tracking module that can lead to a stack-based buffer overflow. The issue occurs when a LAN client initiates a connection to a malicious RTSP server controlled by an attacker. A specially crafted RTSP message may trigger improper memory handling within the kernel module Successful exploitation of this vulnerability may result in a denial-of-service (DoS) condition or allow remote code execution (RCE), potentially leading to full compromise of the device. This vulnerability can be exploited by an unauthenticated attacker under the device's default configuration.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Stack-based Buffer Overflow
The product writes past the end of a buffer that was allocated on the stack.
How developers prevent this class of flaw
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
- Use an abstraction library to abstract away risky APIs. Not a complete solution.
- Implement and perform bounds checking on input.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in TL-WR940N v6
- 7.2 High severity
- 7.2 High severity
Recent Stack-based Buffer Overflow vulnerabilities
- 7.8 High severity
- 8.1 High severity
- 7.5 High severity
- 7.5 High severity
- 9.8 Critical severity
- 7.8 High severity
Spotted an error? Tell us.