CVE-2021-47776: Umbraco CMS v8.14.1 contains a server-side request forgery vulnerability that allows attackers to manipulate b

This week

MEDIUM 5.3REMOTEDOWNGRADE

CVE-2021-47776 is a medium-severity flaw (CVSS 5.3) affecting umbraco cms. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Umbraco CMS v8.14.1 contains a server-side request forgery vulnerability that allows attackers to manipulate baseUrl parameters in multiple dashboard and help controller endpoints. Attackers can craft malicious requests to the GetContextHelpForPage, GetRemoteDashboardContent, and GetRemoteDashboardCss endpoints to trigger unauthorized server-side requests to external hosts.

Why this priority

Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 68%)
CISA exploited list	No
Weakness	CWE-918
Published	2026-01-15
Last modified	2026-10-08

Publisher (CNA): VulnCheck · Vendor: umbraco

Last updated 2026-10-08 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-01-15 16:16 UTCPublished CVE record published
2026-10-08 16:16 UTCUpdated Record last modified

umbraco umbraco cms DOWNGRADE

Affected: 8.14.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.14.1

1. Check installed version

apt-cache policy umbraco-cms || rpm -q umbraco-cms || umbraco-cms --version

2. No fixed release: DOWNGRADE to a release before 8.14.1 (Debian / Ubuntu)

apt-cache madison umbraco-cms sudo apt install umbraco-cms=<VERSION_BEFORE_8.14.1> sudo apt-mark hold umbraco-cms

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list umbraco-cms sudo dnf downgrade umbraco-cms-<VERSION_BEFORE_8.14.1> sudo dnf versionlock add umbraco-cms

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2021-47776?

umbraco cms: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-47776 being exploited?

CVE-2021-47776 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-2021-47776 affect?

CVE-2021-47776 affects umbraco cms. Severity is medium (CVSS 5.3). Umbraco CMS v8.14.1 contains a server-side request forgery vulnerability that allows attackers to manipulate baseUrl parameters in multiple dashboard and help controller endpoints. Attackers can craft malicious requests to the GetContextHel

How urgent is CVE-2021-47776?

Priority 37/100. Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-46616 MEDIUM 5.4 UPGRADE Umbraco is an ASP.NET CMS
CVE-2026-46609 MEDIUM 4.6 UPGRADE Umbraco is an ASP.NET CMS
CVE-2025-66625 MEDIUM 4.9 UPGRADE Umbraco is an ASP.NET CMS
CVE-2025-67288 CRITICAL 10.0 DOWNGRADE An arbitrary file upload vulnerability in Umbraco CMS v16.3.3 allows attackers to execute arbitrary code by up
CVE-2024-55488 MEDIUM 6.5 DOWNGRADE A stored cross-site scripting (XSS) vulnerability in Umbraco CMS v14.3.1 allows attackers to execute arbitrary

References

← Back to latest CVEs