HOMEVULNERABILITIESCVE-2020-36178
CRITICAL

CVE-2020-36178

CWE-78Published: January 6, 2021· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official Description

oal_ipt_addBridgeIsolationRules on TP-Link TL-WR840N 6_EU_0.9.1_4.16 devices allows OS command injection because a raw string entered from the web interface (an IP address field) is used directly for a call to the system library function (for iptables). NOTE: oal_ipt_addBridgeIsolationRules is not the only function that calls util_execSystem.

NVD Source

Technical Analysis

CVE-2020-36178 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

tp-link2 product(s)
tl-wr840n firmwaretl-wr840n
Source: NVD CPE · 2 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://github.com/therealunicornsecurity/therealunicornsecurity.github.io/blob/master/_posts/2020-10-11-TPLink.md
ADVISORYhttps://therealunicornsecurity.github.io/TPLink/
ADVISORYhttps://www.tp-link.com/fr/support/download/tl-wr840n/v6/#Firmware
ADVISORYhttps://github.com/therealunicornsecurity/therealunicornsecurity.github.io/blob/master/_posts/2020-10-11-TPLink.md
ADVISORYhttps://therealunicornsecurity.github.io/TPLink/
ADVISORYhttps://www.tp-link.com/fr/support/download/tl-wr840n/v6/#Firmware

All References (6)

→
https://github.com/therealunicornsecurity/therealunicornsecurity.github.io/blob/master/_posts/2020-10-11-TPLink.mdExploit · Third Party Advisory
→
https://therealunicornsecurity.github.io/TPLink/Exploit · Third Party Advisory
→
https://www.tp-link.com/fr/support/download/tl-wr840n/v6/#FirmwareVendor Advisory
→
https://github.com/therealunicornsecurity/therealunicornsecurity.github.io/blob/master/_posts/2020-10-11-TPLink.mdExploit · Third Party Advisory
→
https://therealunicornsecurity.github.io/TPLink/Exploit · Third Party Advisory
→
https://www.tp-link.com/fr/support/download/tl-wr840n/v6/#FirmwareVendor Advisory

Quick Facts

CVE IDCVE-2020-36178
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-78
CISA KEVNo
Affected1 vendor(s)
PublishedJan 6, 2021

Related CVEs (CWE-78)

CVE-2021-47667
10.0
CVE-2026-10520
KEV10.0
CVE-2025-27364
10.0
CVE-2024-58338
10.0
CVE-2025-2071
10.0
CVE-2012-4177
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2020-36178 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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