CVE-2020-21101: Cross Site Scriptiong vulnerabilityin Screenly screenly-ose all versions, including v1.8.2 (2019-09-25-Screenl

Routine

MEDIUM 5.4DOWNGRADE

CVE-2020-21101 is a medium-severity flaw (CVSS 5.4) affecting screenly. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Cross Site Scriptiong vulnerabilityin Screenly screenly-ose all versions, including v1.8.2 (2019-09-25-Screenly-OSE-lite.img), in the 'Add Asset' page via manipulation of a 'URL' field, which could let a remote malicious user execute arbitrary code.

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.6% (top 51%)
CISA exploited list	No
Weakness	CWE-79
Published	2021-04-29
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: screenly

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

Am I affected?

Timeline

2021-04-29 17:15 UTCPublished CVE record published
2026-06-17 03:03 UTCUpdated Record last modified

screenly screenly DOWNGRADE

Affected: 0.9 · 0.9.1 · 0.10 · 0.11 · 0.12 · 0.12.1 · 0.13 · 0.14

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.9

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.9 (Debian / Ubuntu)

apt-cache madison screenly sudo apt install screenly=<VERSION_BEFORE_0.9> sudo apt-mark hold screenly

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

dnf --showduplicates list screenly sudo dnf downgrade screenly-<VERSION_BEFORE_0.9> sudo dnf versionlock add screenly

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-2020-21101?

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

Is CVE-2020-21101 being exploited?

CVE-2020-21101 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-2020-21101 affect?

CVE-2020-21101 affects screenly. Severity is medium (CVSS 5.4). Cross Site Scriptiong vulnerabilityin Screenly screenly-ose all versions, including v1.8.2 (2019-09-25-Screenly-OSE-lite.img), in the 'Add Asset' page via manipulation of a 'URL' field, which could let a remote malicious user execute arbitr

How urgent is CVE-2020-21101?

Priority 31/100. No elevated risk signals yet.

References

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