CVE-2026-4226Public exploitNetwork attack vector

Web-service crash via unbounded virtual-rule parsing

Published Mar 16, 2026 · Updated Mar 16, 2026

Stack-based buffer overflow in LB-LINK BL-WR9000 2.4.9 allows remote authenticated users to crash the web service through a crafted virtual rule. The bs_GetVirtualSerInfo path reads VirtualRules from NVRAM and uses widthless %[^,] sscanf conversions to copy fields into 8- and 16-byte stack arrays. Configuration-write access is required to plant the oversized rule before /goform/get_virtual_cfg triggers a web-service crash; code execution remains unproven.

CVSS severity9.8
Critical
EPSS probability0.69%
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 LB-LINK BL-WR9000 2.4.9 allows remote authenticated users to crash the web service through a crafted virtual rule. The bs_GetVirtualSerInfo path reads VirtualRules from NVRAM and uses widthless %[^,] sscanf conversions to copy fields into 8- and 16-byte stack arrays. Configuration-write access is required to plant the oversized rule before /goform/get_virtual_cfg triggers a web-service crash; code execution remains unproven.

The record

CVE
CVE-2026-4226
Published
Mar 16, 2026
Updated
Mar 16, 2026
Vendor
LB-LINK
Product
BL-WR9000
Classifications
CWE-119, CWE-787, CWE-121, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 16, 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=2.4.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

LB-LINK · BL-WR9000version=2.4.9

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.0VulDBAV:N/AC:L/Au:S/C:C/I:C/A:C
8.8VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.4VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
CWE-787Out-of-bounds Write
CWE-121Stack-based Buffer Overflow
T1499.004Application or System Exploitation

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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