Unauthorized debug access via predictable default key
Published Apr 23, 2026 · Updated Apr 23, 2026
Authentication bypass in TP-Link TL-WR841N v13 before 0.9.1 Build 20231120 Rel.62366 allows attackers on the local network to access TDDPv2. TDDPv2 encrypts debug traffic with DES-CBC using a key derived from the default web-management credentials, so devices retaining that configuration expose a predictable protocol key. No prior authentication or user interaction is required, but network adjacency is required; successful access reads debug data, changes certain configuration values, and reboots the router.
Summary
What happened
Authentication bypass in TP-Link TL-WR841N v13 before 0.9.1 Build 20231120 Rel.62366 allows attackers on the local network to access TDDPv2. TDDPv2 encrypts debug traffic with DES-CBC using a key derived from the default web-management credentials, so devices retaining that configuration expose a predictable protocol key. No prior authentication or user interaction is required, but network adjacency is required; successful access reads debug data, changes certain configuration values, and reboots the router.
The record
- CVE
- CVE-2026-5039
- Published
- Apr 23, 2026
- Updated
- Apr 23, 2026
- Vendor
- TP-Link Systems Inc.
- Product
- TL-WR841N
- Classifications
- CWE-1394, T1499
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 23, 2026CVE publishedPublication date reported by the CVE source.
- Apr 23, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=0 <0.9.1 Build 20231120 Rel.62366
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
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Technologies
Your stack
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Your stack
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