CVE-2026-18588Public exploitNetwork attack vector

Root command execution via unbounded CGI body read

Published Aug 3, 2026 · Updated Aug 3, 2026

Stack-based buffer overflow in Wavlink WL-NU516U1 firmware 708c073-mt7628 allows remote attackers to execute code as root. The nas.cgi main function passes the attacker-controlled CONTENT_LENGTH value plus one to fgets, which writes the POST body into a fixed 516-byte stack buffer without an upper-bound check. A valid session is normally required; MeshMode=2 permits an authentication bypass, and a successful overwrite grants root control.

CVSS severity9.3
Critical
EPSS probability0.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in Wavlink WL-NU516U1 firmware 708c073-mt7628 allows remote attackers to execute code as root. The nas.cgi main function passes the attacker-controlled CONTENT_LENGTH value plus one to fgets, which writes the POST body into a fixed 516-byte stack buffer without an upper-bound check. A valid session is normally required; MeshMode=2 permits an authentication bypass, and a successful overwrite grants root control.

The record

CVE
CVE-2026-18588
Published
Aug 3, 2026
Updated
Aug 3, 2026
Vendor
Wavlink
Product
WL-NU516U1
Classifications
CWE-121, CWE-119, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=708c073-mt7628

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Wavlink · WL-NU516U1version=708c073-mt7628

Published CVSS scores

9.8VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.3VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
10.0VulDBAV:N/AC:L/Au:N/C:C/I:C/A:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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