TL-MR6400 v7.0: NULL Pointer Dereference
CVE-2026-17251 is a high-severity NULL pointer dereference vulnerability in TL-MR6400 v7.0 from TP-Link, with a CVSS 4.0 base score of 7.1 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists version 1.9.0 Build 260714 as the first without the flaw, so updating TL-MR6400 v7.0 to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.47% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update TL-MR6400 v7.0 to 1.9.0 Build 260714 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| TP-Link | TL-MR6400 v7.0 | before 1.9.0 Build 260714 | 1.9.0 Build 260714 |
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
- AdjacentThe attacker must be on the same local network segment.
- 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
- NoneNo action by a victim is required.
- Confidentiality (vulnerable system)
- NoneNo loss of confidentiality on the vulnerable system.
- Integrity (vulnerable system)
- NoneNo 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:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/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
A NULL pointer dereference vulnerability exists in the HTTP request parsing functionality of TL-MR6400 v7. An unauthenticated remote attacker can trigger the vulnerability by sending a specially crafted HTTP request containing a malformed session cookie header. Successful exploitation may cause the HTTP service process to crash, resulting in a denial-of-service condition and temporary loss of management or CGI functionality until service recovery.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: NULL Pointer Dereference
The product dereferences a pointer that it expects to be valid but is NULL.
How developers prevent this class of flaw
- For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished.
- Select a programming language that is not susceptible to these issues.
- Check the results of all functions that return a value and verify that the value is non-null before acting upon it.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in TL-MR6400 v7.0
- 7.1 High severity
- 8.5 High severity
Recent NULL Pointer Dereference vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.8 High severity
- 8.2 High severity
- 7.8 High severity
- 7.5 High severity
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