CVE-2020-9309: Silverstripe CMS through 4.5 can be susceptible to script execution from malicious upload contents under allow

This month

HIGH 8.8UPGRADEUPGRADE

CVE-2020-9309 is a high-severity flaw (CVSS 8.8) affecting mimevalidator, recipe. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Silverstripe CMS through 4.5 can be susceptible to script execution from malicious upload contents under allowed file extensions (for example HTML code in a TXT file). When these files are stored as protected or draft files, the MIME detection can cause browsers to execute the file contents. Uploads stored as protected or draft files are allowed by default for authorised users only, but can also be enabled through custom logic as well as modules

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.8% (top 21%)
CISA exploited list	No
Weakness	CWE-434
Published	2020-07-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: silverstripe

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

Am I affected?

Timeline

2020-07-15 21:15 UTCPublished CVE record published
2026-06-17 03:27 UTCUpdated Record last modified

silverstripe mimevalidator UPGRADE

Affected: < 2.0.0

Fixed in: 2.0.0

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 2.0.0 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade mimevalidator

Note

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

silverstripe recipe UPGRADE

Affected: >= 4.0.0 and < 4.6.0

Fixed in: 4.6.0

Safe to downgrade to: a release before 4.0.0

1. Check installed version

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

2. UPGRADE to 4.6.0 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade recipe

Note

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

3. If no update is available yet, DOWNGRADE to a release before 4.0.0 (Debian / Ubuntu)

apt-cache madison recipe sudo apt install recipe=<VERSION_BEFORE_4.0.0> sudo apt-mark hold recipe

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list recipe sudo dnf downgrade recipe-<VERSION_BEFORE_4.0.0> sudo dnf versionlock add recipe

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-2020-9309?

mimevalidator: upgrade to 2.0.0; recipe: upgrade to 4.6.0. Exact commands for each OS are on this page.

Is CVE-2020-9309 being exploited?

CVE-2020-9309 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-2020-9309 affect?

CVE-2020-9309 affects mimevalidator, recipe. Severity is high (CVSS 8.8). Silverstripe CMS through 4.5 can be susceptible to script execution from malicious upload contents under allowed file extensions (for example HTML code in a TXT file). When these files are stored as protected or draft files, the MIME detect

How urgent is CVE-2020-9309?

Priority 51/100. High severity

References

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