How severe is CVE-2020-36178?

CVE-2020-36178 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-36178 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 10% (95th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-36178?

CVE-2020-36178 affects Tp-link Tl-wr840n Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-36178?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2020-36178 published?

CVE-2020-36178 was published on 2021-01-06 and last updated on 2026-06-17.

CVE-2020-36178

CVE-2020-36178 is a critical-severity vulnerability in Tp-link Tl-wr840n Firmware with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-78.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 10.0
EPSS exploit prediction: 10% (95th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-78
Affected product: Tp-link Tl-wr840n Firmware
Published: 2021-01-06
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2020-36178?: 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.
How severe is CVE-2020-36178?: CVE-2020-36178 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-36178 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 10% (95th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-36178?: CVE-2020-36178 affects Tp-link Tl-wr840n Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-36178?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2020-36178 published?: CVE-2020-36178 was published on 2021-01-06 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:tp-link:tl-wr840n_firmware:6_eu_0.9.1_4.16:*:*:*:*:*:*:*

More vulnerabilities in Tp-link Tl-wr840n Firmware

CVE-2022-25064 — Critical (CVSS 9.8): TP-LINK TL-WR840N(ES)_V6.20_180709 was discovered to contain a remote code execution (RCE) vulnerability via the…
CVE-2022-25061 — Critical (CVSS 9.8): TP-LINK TL-WR840N(ES)_V6.20_180709 was discovered to contain a command injection vulnerability via the component…
CVE-2022-25060 — Critical (CVSS 9.8): TP-LINK TL-WR840N(ES)_V6.20_180709 was discovered to contain a command injection vulnerability via the component…
CVE-2021-41653 — Critical (CVSS 9.8): The PING function on the TP-Link TL-WR840N EU v5 router with firmware through TL-WR840N(EU)_V5_171211 is vulnerable to…
CVE-2018-11714 — Critical (CVSS 9.8): An issue was discovered on TP-Link TL-WR840N v5 00000005 0.9.1 3.16 v0001.0 Build 170608 Rel.58696n and TL-WR841N v13…
CVE-2023-39471 — High (CVSS 8.8): TP-Link TL-WR841N ated_tp Command Injection Remote Code Execution Vulnerability. This vulnerability allows…

All CVEs affecting Tp-link Tl-wr840n Firmware →

Other CWE-78 (OS Command Injection) vulnerabilities

CVE-2026-19188 — Critical (CVSS 10.0): A critical OS command injection vulnerability has been identified in the Haiwell IoT Cloud HMI Gateway product. The…
CVE-2026-48362 — Critical (CVSS 10.0): ColdFusion is affected by an Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')…
CVE-2026-16812 — Critical (CVSS 10.0): VeloCloud Orchestrator (VCO) on-prem has a security issue where this issue may allow a remote attacker to access…
CVE-2026-6516 — Critical (CVSS 10.0): Zohocorp ManageEngine ADAudit Plus versions before 8606 are affected by Unauthenticated Remote code execution due to…
CVE-2026-46339 — Critical (CVSS 10.0): 9Router is an AI router & token saver. From 0.4.30 until 0.4.37, 9Router's src/proxy.js middleware did not protect…
CVE-2026-59726 — Critical (CVSS 10.0): Ruflo is an agent meta-harness for Claude Code and Codex. Prior to 3.16.3, ruflo's default docker-compose deployment…

Browse all CWE-78 (OS Command Injection) vulnerabilities →