What is CVE-2021-26827?

CVE-2021-26827 is a high-severity vulnerability in TP-Link Tl-Wr2041\+, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 7.5/10. Published 2021-04-14.

How severe is CVE-2021-26827?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2021-26827 known to be exploited?

2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Buffer overflow in TP-Link Tl-Wr2041\+

CVE-2021-26827

Buffer Overflow in TP-Link WR2041 v1 firmware for the TL-WR2041+ router allows remote attackers to cause a Denial-of-Service (DoS) by sending an HTTP request with a very long "ssid" parameter to the "/userRpm/popupSiteSurveyRpm.html" webpage, which crashes the router.

Vulnerability class: Buffer Overflow

Published 2021-04-14 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.017 (76.4th percentile), scored 2026-10-01.

Low probability of exploitation in the next 30 days, but still tracked. 76th percentile — 76.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.017 · newest: 0.017 · change: 0.000

Affected products

Weakness classification (CWE)

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

Public proof-of-concept exploits

References

github.com/GD008/vuln/blob/main/tplink_wr2041/tplink_WR2041pv1.md (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-26827?: CVE-2021-26827 is a high-severity vulnerability in TP-Link Tl-Wr2041\+, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 7.5/10. Published 2021-04-14.
How severe is CVE-2021-26827?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2021-26827 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.