Buffer overflow in Wavlink Wl-Nu516u1
CVE-2026-4861
A weakness has been identified in Wavlink WL-NU516U1 260227. This vulnerability affects the function ftext of the file /cgi-bin/nas.cgi. This manipulation of the argument Content-Length causes stack-based buffer overflow. The attack can be initiated remotely. The exploit has been made available to the public and could be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.009 (58.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 59th percentile — 58.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.011 · newest: 0.009 · change: -0.002
Affected products
- Wavlink Wl-Nu516u1 — versions 260227
- Wavlink Wl-Nu516u1 Firmware — versions m16u1_v260227
Weakness classification (CWE)
Public proof-of-concept exploits
References
- vuldb.com/ (technical-description, VDB Entry, Third Party Advisory, vdb-entry)
- vuldb.com/ (signature, Permissions Required, permissions-required, VDB Entry)
- vuldb.com/ (VDB Entry, Third Party Advisory, third-party-advisory)
- github.com/Wlz1112/WAVLINK-NU516U1-V260227/blob/main/Content-Length.md (Exploit, Third Party Advisory, exploit)
Frequently asked questions
- What is CVE-2026-4861?
- CVE-2026-4861 is a high-severity vulnerability in Wavlink Wl-Nu516u1, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 8.8/10. Published 2026-03-26.
- How severe is CVE-2026-4861?
- High severity. CVSS v3 base score is 8.8 out of 10.
- Is CVE-2026-4861 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.