CVE-2021-41110: cwlviewer is a web application to view and share Common Workflow Language workflows

Q: How do I fix CVE-2021-41110?

cwlviewer: upgrade to 1.3.1. Exact commands for each OS are on this page.

Q: Is CVE-2021-41110 being exploited?

CVE-2021-41110 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-2021-41110 affect?

CVE-2021-41110 affects cwlviewer. Severity is critical (CVSS 9.1). cwlviewer is a web application to view and share Common Workflow Language workflows. Versions prior to 1.3.1 contain a Deserialization of Untrusted Data vulnerability. Commit number f6066f09edb70033a2ce80200e9fa9e70a5c29de (dated 2021-09-30

Q: How urgent is CVE-2021-41110?

Priority 63/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

CRITICAL 9.1REMOTEUPGRADE

CVE-2021-41110 is a critical-severity flaw (CVSS 9.1) affecting cwlviewer. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

cwlviewer is a web application to view and share Common Workflow Language workflows. Versions prior to 1.3.1 contain a Deserialization of Untrusted Data vulnerability. Commit number f6066f09edb70033a2ce80200e9fa9e70a5c29de (dated 2021-09-30) contains a patch. There are no available workarounds aside from installing the patch. The SnakeYaml constructor, by default, allows any data to be parsed. To fix the issue the object needs to be created with

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	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.8% (top 13%)
CISA exploited list	No
Weakness	CWE-502
Published	2021-10-01
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: commonwl

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

Am I affected?

Timeline

2021-10-01 13:15 UTCPublished CVE record published
2026-06-17 04:07 UTCUpdated Record last modified

commonwl cwlviewer UPGRADE

Affected: < 1.3.1

Fixed in: 1.3.1

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 1.3.1 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade cwlviewer

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-2021-41110?

cwlviewer: upgrade to 1.3.1. Exact commands for each OS are on this page.

Is CVE-2021-41110 being exploited?

CVE-2021-41110 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-2021-41110 affect?

CVE-2021-41110 affects cwlviewer. Severity is critical (CVSS 9.1). cwlviewer is a web application to view and share Common Workflow Language workflows. Versions prior to 1.3.1 contain a Deserialization of Untrusted Data vulnerability. Commit number f6066f09edb70033a2ce80200e9fa9e70a5c29de (dated 2021-09-30

How urgent is CVE-2021-41110?

Priority 63/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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