CVE-2026-31027: TOTOlink A3600R v5.9c.4959 contains a buffer overflow vulnerability in the setAppEasyWizardConfig interface of

This week

CRITICAL 9.8REMOTEMITIGATE

CVE-2026-31027 is a critical-severity flaw (CVSS 9.8) affecting a3600r firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

TOTOlink A3600R v5.9c.4959 contains a buffer overflow vulnerability in the setAppEasyWizardConfig interface of /lib/cste_modules/app.so. The vulnerability occurs because the rootSsid parameter is not properly validated for length, allowing remote attackers to trigger a buffer overflow, potentially leading to arbitrary code execution or denial of service.

Why this priority

Critical severity
Public exploit reference
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 52%)
CISA exploited list	No
Weakness	CWE-120
Published	2026-04-01
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: totolink

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-01 16:23 UTCPublished CVE record published
2026-06-17 10:33 UTCUpdated Record last modified

totolink a3600r firmware MITIGATE

Affected: 5.9c.4959

Fixed in: no fixed release known

Safe to downgrade to: a release before 5.9c.4959

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · python-googleapis-common-protos · FIXED · 1.75.5-1.fc46~bootstrap · FEDORA-2026-d911c4c4e6 · source

sudo dnf upgrade --advisory=FEDORA-2026-d911c4c4e6

Fedora ELN · see advisory · FIXED · FEDORA-2026-e3987c278f · source

sudo dnf upgrade --advisory=FEDORA-2026-e3987c278f

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: github.com/SunnyYANGyaya/cuicuishark-sheep-fishIOT/blob/main/ToTolink/A3600R/rootSsid-setA

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-31027?

a3600r firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-31027 being exploited?

CVE-2026-31027 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-31027 affect?

CVE-2026-31027 affects a3600r firmware. Severity is critical (CVSS 9.8). TOTOlink A3600R v5.9c.4959 contains a buffer overflow vulnerability in the setAppEasyWizardConfig interface of /lib/cste_modules/app.so. The vulnerability occurs because the rootSsid parameter is not properly validated for length, allowing

How urgent is CVE-2026-31027?

Priority 59/100. Critical severity; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-5020 MEDIUM 6.3 MITIGATE A vulnerability was detected in Totolink A3600R 4.1.2cu.5182_B20201102

References

← Back to latest CVEs