CVE-2021-41653
CriticalExploitedThe PING function on the TP-Link TL-WR840N EU v5 router with firmware through TL-WR840N(EU)_V5_171211 is vulnerable to remote code execution via a crafted payload in an IP address input field.
Published Nov 13, 2021 · Updated Jul 9, 2026
Key Facts
Patch immediately- CVE-2021-41653 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Tl-Wr840n Firmware (Tp-Link).
- It is exploited in the wild, listed in Industry KEV feed, CIRCL KEV since Dec 8, 2021. No public exploit code is known.
- EPSS estimates a 76% probability of exploitation in the next 30 days.
- Fixed versions are available, including Tl-Wr840n Firmware <=tl-wr840n\(eu\)_v5_171211, Tl-Wr840n Firmware tl-wr840n\(eu\)_v5_171211.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
76%
Higher than 99.5% of all scored CVEs
Exploited in the wild
Yes
2 catalog listings
Public exploit code
None known
Get the full CVE-2021-41653 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
The PING function on the TP-Link TL-WR840N EU v5 router with firmware through TL-WR840N(EU)_V5_171211 is vulnerable to remote code execution via a crafted payload in an IP address input field.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| Industry KEV feed | Dec 8, 2021 | n/a | Not reported |
| CIRCL KEV | Oct 14, 2023 | n/a | Not reported |
Required action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Affected Products
1 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Tl-Wr840n FirmwareTp-Link | See advisory | tl-wr840n\(eu\)_v5_171211 |
Patched Releases
Tl-Wr840n Firmware
<=tl-wr840n\(eu\)_v5_171211
Timeline
Publicly disclosed
Nov 13, 2021
Added to Industry KEV feed
Dec 8, 2021
Added to CIRCL KEV
Oct 14, 2023
Last updated
Jul 9, 2026
Weakness Type
- CWE-94 Improper Control of Generation of Code ('Code Injection')
References
- advisoryhttps://www.tp-link.com/us/press/security-advisory/
- advisoryhttp://tp-link.com
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
- exploitVulnCheck exploitation report
FAQ
Common Questions.
The PING function on the TP-Link TL-WR840N EU v5 router with firmware through TL-WR840N(EU)_V5_171211 is vulnerable to remote code execution via a crafted payload in an IP address input field.
Affected: Tl-Wr840n Firmware (Tp-Link). The full list is in the CVE brief.
It is exploited in the wild, listed in Industry KEV feed, CIRCL KEV since Dec 8, 2021.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including Tl-Wr840n Firmware <=tl-wr840n\(eu\)_v5_171211, Tl-Wr840n Firmware tl-wr840n\(eu\)_v5_171211.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
Is CVE-2021-41653 Running On Your Attack Surface?
Brandefense maps vulnerabilities like this one to your internet-facing assets and tells you exactly where to patch.
Request A Demo