CVE-2018-20872: DrayTek routers before 2018-05-23 allow CSRF attacks to change DNS or DHCP settings, a related issue to CVE-20

Q: How do I fix CVE-2018-20872?

draytekl firmware: upgrade to 2018-05-23. Exact commands for each OS are on this page.

Q: Is CVE-2018-20872 being exploited?

CVE-2018-20872 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2018-20872 affect?

CVE-2018-20872 affects draytekl firmware. Severity is medium (CVSS 6.5). DrayTek routers before 2018-05-23 allow CSRF attacks to change DNS or DHCP settings, a related issue to CVE-2017-11649.

Q: How urgent is CVE-2018-20872?

Priority 34/100. No elevated risk signals yet.

Routine

MEDIUM 6.5UPGRADE

CVE-2018-20872 is a medium-severity flaw (CVSS 6.5) affecting draytekl firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

DrayTek routers before 2018-05-23 allow CSRF attacks to change DNS or DHCP settings, a related issue to CVE-2017-11649.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.5% (top 57%)
CISA exploited list	No
Weakness	CWE-352
Published	2019-07-31
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: i-lan

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

Am I affected?

Timeline

2019-07-31 18:15 UTCPublished CVE record published
2026-06-17 01:53 UTCUpdated Record last modified

i-lan draytekl firmware UPGRADE

Affected: < 2018-05-23

Fixed in: 2018-05-23

Safe to downgrade to: no unaffected older release

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.

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-2018-20872?

draytekl firmware: upgrade to 2018-05-23. Exact commands for each OS are on this page.

Is CVE-2018-20872 being exploited?

CVE-2018-20872 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-2018-20872 affect?

CVE-2018-20872 affects draytekl firmware. Severity is medium (CVSS 6.5). DrayTek routers before 2018-05-23 allow CSRF attacks to change DNS or DHCP settings, a related issue to CVE-2017-11649.

How urgent is CVE-2018-20872?

Priority 34/100. No elevated risk signals yet.

References

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