CVE-2026-31027Public exploitNetwork attack vector

Unauthenticated code execution via unbounded rootSsid formatting

Published Apr 1, 2026 · Updated Apr 1, 2026

Stack buffer overflow in TOTOlink A3600R firmware 5.9c.4959 allows remote attackers to execute code or crash the router via rootSsid. setAppEasyWizardConfig passes rootSsid plus the _5G suffix to sprintf for storage in the 32-byte stack buffer v36 without checking the resulting length. The vulnerable branch requires functionType of at least 2 and rootFlag equal to 1; no authentication or user interaction is required.

CVSS severity9.8
Critical
EPSS probability0.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack buffer overflow in TOTOlink A3600R firmware 5.9c.4959 allows remote attackers to execute code or crash the router via rootSsid. setAppEasyWizardConfig passes rootSsid plus the _5G suffix to sprintf for storage in the 32-byte stack buffer v36 without checking the resulting length. The vulnerable branch requires functionType of at least 2 and rootFlag equal to 1; no authentication or user interaction is required.

The record

CVE
CVE-2026-31027
Published
Apr 1, 2026
Updated
Apr 1, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-120, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 1, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 1, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

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