NVD / CVE Program· CNA mitre

CVE-2021-46122: Tp-Link TL-WR840N (EU) v6.20 Firmware (0.9.1 4.17 v0001.0 Build 201124 Rel.64328n) is vulnerable to Buffer Overflow via the Password reset…

HighCVSS 7.2 · v3.1—No exploit No fix recorded

Noroxi assessment

Priority: Monitor (action score 28/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 1.5% (FIRST EPSS); higher than 75.4% of all records.
Anyone who can reach it over the internet can trigger it. Administrator privileges are required. No user action is required. No special conditions are required; it is repeatable.
According to the record, no fixed version is available yet.

Low priority for now. Update when a fix is released; follow the vendor's advisory.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Tp-Link TL-WR840N (EU) v6.20 Firmware (0.9.1 4.17 v0001.0 Build 201124 Rel.64328n) is vulnerable to Buffer Overflow via the Password reset feature.

Memory safety

Published: Apr 18, 2022
Updated: Jun 17, 2026
EPSS: 1.5% · 75th percentile
CWE: CWE-120

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 28 / 40 · 7.2 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 1.5%

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
No fixed version yet

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
tp-link	tl-wr840n firmware	cpe:2.3:o:tp-link:tl-wr840n_firmware
tp-link	tl-wr840n	cpe:2.3:h:tp-link:tl-wr840n

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

tp-link tl-wr840n firmware0.9.1_4.17_v0001.0

Same product

tp-link: all records

Other highest-scoring records for the same primary product.

CVE-2021-41653The PING function on the TP-Link TL-WR840N EU v5 router with firmware through TL-WR840N(EU)_V5_171211 is vulnerable to remote code…
62This week
CVE-2018-11714An 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 00000013 0.9.1 4.16…
59Plan
CVE-2022-25061TP-LINK TL-WR840N(ES)_V6.20_180709 was discovered to contain a command injection vulnerability via the component oal_setIp6DefaultRoute.
57Plan

Published before and after this one in the same product

← EarlierCVE-2022-26641Mar 28, 2022 · TP-LINK TL-WR840N(ES)_V6.20 was discovered to contain a buffer overflow via the httpRemotePort parameter.
28Monitor
← EarlierCVE-2022-26642Mar 28, 2022 · TP-LINK TL-WR840N(ES)_V6.20 was discovered to contain a buffer overflow via the X_TP_ClonedMACAddress parameter.
28Monitor
Later →CVE-2022-29402May 25, 2022 · TP-Link TL-WR840N EU v6.20 was discovered to contain insecure protections for its UART console.
27Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
Administrator privileges are required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Network
Attack complexity: Low
Privileges required: High
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-120 · Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Root cause

When data is copied, the source length is not compared with the size of the destination buffer. Excess data overwrites adjacent memory.

The bug in code

The whole CWE-120 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1char buf[256];
2memcpy(buf, pkt->data, pkt->len);

Fixed

1char buf[256];
2if (pkt->len > sizeof(buf)) {
3  return -EINVAL;
4}
5memcpy(buf, pkt->data, pkt->len);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

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Change log (0)

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

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