CVE-2025-67186: TOTOLINK A950RG V4.1.2cu.5204_B20210112 contains a buffer overflow vulnerability in the setUrlFilterRules inte

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CRITICAL 9.8REMOTEMITIGATE

CVE-2025-67186 is a critical-severity flaw (CVSS 9.8) affecting a950rg firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

TOTOLINK A950RG V4.1.2cu.5204_B20210112 contains a buffer overflow vulnerability in the setUrlFilterRules interface of /lib/cste_modules/firewall.so. The vulnerability occurs because the `url` 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	0.8% (top 43%)
CISA exploited list	No
Weakness	CWE-120
Published	2026-02-03
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

2026-02-03 18:16 UTCPublished CVE record published
2026-06-17 09:57 UTCUpdated Record last modified

totolink a950rg firmware MITIGATE

Affected: 4.1.2cu.5204_b20210112

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.1.2cu.5204_b20210112

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 · proftpd · FIXED · 1.3.9e-2.fc46 · FEDORA-2026-fcb0a25c2f · source

sudo dnf upgrade --advisory=FEDORA-2026-fcb0a25c2f

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-2025-67186?

a950rg firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2025-67186 being exploited?

CVE-2025-67186 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-2025-67186 affect?

CVE-2025-67186 affects a950rg firmware. Severity is critical (CVSS 9.8). TOTOLINK A950RG V4.1.2cu.5204_B20210112 contains a buffer overflow vulnerability in the setUrlFilterRules interface of /lib/cste_modules/firewall.so. The vulnerability occurs because the `url` parameter is not properly validated for length,

How urgent is CVE-2025-67186?

Priority 61/100. Critical severity; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Related CVEs

CVE-2025-44655 CRITICAL 9.8 MITIGATE MITIGATE In TOTOLink A7100RU V7.4, A950RG V5.9, and T10 V5.9, the chroot_local_user option is enabled in the vsftpd.con
CVE-2025-67189 MEDIUM 6.5 MITIGATE A buffer overflow vulnerability exists in the setParentalRules interface of TOTOLINK A950RG V4.1.2cu.5204_B202
CVE-2025-67188 CRITICAL 9.8 MITIGATE A buffer overflow vulnerability exists in TOTOLINK A950RG V4.1.2cu.5204_B20210112
CVE-2025-67187 CRITICAL 9.8 MITIGATE A stack-based buffer overflow vulnerability was identified in TOTOLINK A950RG V4.1.2cu.5204_B20210112
CVE-2025-60702 MEDIUM 6.5 MITIGATE A command injection vulnerability exists in the TOTOLINK A950RG Router firmware V5.9c.4592_B20191022_ALL withi

References

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