TL-WL841N v13: Use of Default Cryptographic Key
CVE-2026-5039 is a high-severity use of default cryptographic key vulnerability in TL-WL841N v13 from TP-Link, with a CVSS 3.1 base score of 8.8 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 0.9.1 Build 20231120 Rel.62366 as the first without the flaw, so updating TL-WL841N v13 to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.13% 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-WL841N v13 to 0.9.1 Build 20231120 Rel.62366 or a later version.
- Update Tl-wr841n Firmware to 231120 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| TP-Link | TL-WL841N v13 | before 0.9.1 Build 20231120 Rel.62366 | 0.9.1 Build 20231120 Rel.62366 |
| TP-Link | Tl-wr841n Firmware | before 231120 | 231120 |
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.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 6.1 | Medium | CNA |
| CVSS 3.1 | 8.8 | High | NVD |
Official description
TP-Link TL-WR841N v13 uses DES-CBC encryption in the TDDPv2 debug protocol with a cryptographic key derived from default web management credentials, making the key predictable if device is left in default configuration. A network-adjacent attacker can exploit this weakness to gain unauthorized access to the protocol, read debug data, modify certain device configuration values, and trigger device reboot, resulting in loss of integrity and a denial-of-service condition.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use of Default Cryptographic Key
The product uses a default cryptographic key for potentially critical functionality.
How developers prevent this class of flaw
- Prohibit use of default, hard-coded, or other values that do not vary for each installation of the product - especially for separate organizations.
- Force the administrator to change the credential upon installation.
- The product administrator could change the defaults upon installation or during operation.
More Use of Default Cryptographic Key vulnerabilities (CWE-1394)
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
Recent Use of Default Cryptographic Key vulnerabilities
- 9.1 Critical severity
- 9.8 Critical severity
- 8.1 High severity
- 9.1 Critical severity
- 9.1 Critical severity
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