CVE-2026-4861: Wavlink WL-NU516U1 nas.cgi ftext stack-based overflow

Vulnerability summary

CVE-2026-4861 is a high (CVSS 9.0) vulnerability in wavlink wl-nu516u1_firmware. EPSS estimates a 1.06% chance of exploitation in the next 30 days, higher than 64.1% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 26-03-2026
   PublishedVulnerability first disclosed.
2. 26-03-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-119Improper Restriction of Operations within the Bounds of a Memory BufferThe product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
• CWE-121Stack-based Buffer OverflowA stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).