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Fencer Vulns
high 8.8

CVE-2026-5039 json

Predictable Default Cryptographic Key Used for DES Encryption in TP-Link TL-WL841N

published 2026-04-23 6 mo ago modified 2026-10-25 14 d ago also EUVD-2026-25250

cvss
8.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

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.

Patch / fix

  • TP-Link Systems Inc. TL-WL841N v13 0.9.1 Build 20231120 Rel.62366

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa vex VA-26-119-02 updated cvss 8.3

TP-Link WR841N Router multiple vulnerabilities

  • TP-Link Systems Inc. TL-WR841N v13 <0.9.1 Build 20231120 Rel.62366
    affected: vendor fix tp-link.com
  • TP-Link Systems Inc. TL-WR841N v13 0.9.1 Build 20231120 Rel.62366
    fixed: vendor fix tp-link.com

From CISA ICS and IT advisories (CSAF, https://github.com/cisagov/CSAF), a U.S. Government work; changed: reduced to products, statuses and remediations. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
6 mo ago

Exploit prediction

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 6.1 CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N
CNA 4.0 6.1 CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:L/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
NVD 3.1 8.8 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • TP-Link Systems Inc. TL-WL841N v13

Classification

Weakness
  • CWE-1394 Use of Default Cryptographic Key

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.