CVE-2020-12471: MonoX through 5.1.40.5152 allows remote code execution via HTML5Upload.ashx or Pages/SocialNetworking/lng/en-U

Q: How do I fix CVE-2020-12471?

monox: upgrade to newer than 5.1.40.5152. Exact commands for each OS are on this page.

Q: Is CVE-2020-12471 being exploited?

CVE-2020-12471 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-2020-12471 affect?

CVE-2020-12471 affects monox. Severity is critical (CVSS 9.8). MonoX through 5.1.40.5152 allows remote code execution via HTML5Upload.ashx or Pages/SocialNetworking/lng/en-US/PhotoGallery.aspx because of deserialization in ModuleGallery.HTML5Upload, ModuleGallery.SilverLightUploadModule, HTML5Upload, a

Q: How urgent is CVE-2020-12471?

Priority 66/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2020-12471 is a critical-severity flaw (CVSS 9.8) affecting monox. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

MonoX through 5.1.40.5152 allows remote code execution via HTML5Upload.ashx or Pages/SocialNetworking/lng/en-US/PhotoGallery.aspx because of deserialization in ModuleGallery.HTML5Upload, ModuleGallery.SilverLightUploadModule, HTML5Upload, and SilverLightUploadHandler.

Why this priority

Critical severity
Public exploit reference
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	2.8% (top 14%)
CISA exploited list	No
Weakness	CWE-502
Published	2020-04-29
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: mono

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

Am I affected?

Timeline

2020-04-29 21:15 UTCPublished CVE record published
2026-06-17 02:51 UTCUpdated Record last modified

mono monox UPGRADE

Affected: <= 5.1.40.5152

Fixed in: newer than 5.1.40.5152

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy monox || rpm -q monox || monox --version

2. UPGRADE to newer than 5.1.40.5152 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade monox

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade monox

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2020-12471?

monox: upgrade to newer than 5.1.40.5152. Exact commands for each OS are on this page.

Is CVE-2020-12471 being exploited?

CVE-2020-12471 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-2020-12471 affect?

CVE-2020-12471 affects monox. Severity is critical (CVSS 9.8). MonoX through 5.1.40.5152 allows remote code execution via HTML5Upload.ashx or Pages/SocialNetworking/lng/en-US/PhotoGallery.aspx because of deserialization in ModuleGallery.HTML5Upload, ModuleGallery.SilverLightUploadModule, HTML5Upload, a

How urgent is CVE-2020-12471?

Priority 66/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2020-12473 HIGH 7.2 UPGRADE MonoX through 5.1.40.5152 allows admins to execute arbitrary programs by reconfiguring the Converter Executabl
CVE-2020-12472 MEDIUM 5.4 UPGRADE MonoX through 5.1.40.5152 allows stored XSS via User Status, Blog Comments, or Blog Description.
CVE-2020-12470 HIGH 7.2 UPGRADE MonoX through 5.1.40.5152 allows administrators to execute arbitrary code by modifying an ASPX template.

References

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