CVE-2021-28667: StackStorm before 3.4.1, in some situations, has an infinite loop that consumes all available memory and disk

Q: How do I fix CVE-2021-28667?

stackstorm: upgrade to 3.4.1. Exact commands for each OS are on this page.

Q: Is CVE-2021-28667 being exploited?

CVE-2021-28667 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-2021-28667 affect?

CVE-2021-28667 affects stackstorm. Severity is high (CVSS 7.5). StackStorm before 3.4.1, in some situations, has an infinite loop that consumes all available memory and disk space. This can occur if Python 3.x is used, the locale is not utf-8, and there is an attempt to log Unicode data (from an action

Q: How urgent is CVE-2021-28667?

Priority 52/100. High severity; Remotely exploitable, no login, no user action

This month

HIGH 7.5REMOTEUPGRADE

CVE-2021-28667 is a high-severity flaw (CVSS 7.5) affecting stackstorm. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

StackStorm before 3.4.1, in some situations, has an infinite loop that consumes all available memory and disk space. This can occur if Python 3.x is used, the locale is not utf-8, and there is an attempt to log Unicode data (from an action or rule name).

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.5% (top 15%)
CISA exploited list	No
Weakness	CWE-835
Published	2021-03-18
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: stackstorm

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

Am I affected?

Timeline

2021-03-18 03:15 UTCPublished CVE record published
2026-06-17 03:46 UTCUpdated Record last modified

stackstorm stackstorm UPGRADE

Affected: < 3.4.1

Fixed in: 3.4.1

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 3.4.1 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade stackstorm

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-2021-28667?

stackstorm: upgrade to 3.4.1. Exact commands for each OS are on this page.

Is CVE-2021-28667 being exploited?

CVE-2021-28667 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-2021-28667 affect?

CVE-2021-28667 affects stackstorm. Severity is high (CVSS 7.5). StackStorm before 3.4.1, in some situations, has an infinite loop that consumes all available memory and disk space. This can occur if Python 3.x is used, the locale is not utf-8, and there is an attempt to log Unicode data (from an action

How urgent is CVE-2021-28667?

Priority 52/100. High severity; Remotely exploitable, no login, no user action

Software pages

Python vulnerabilities

Related CVEs

CVE-2022-44009 HIGH 7.5 DOWNGRADE Improper access control in Key-Value RBAC in StackStorm version 3.7.0 didn't check the permissions in Jinja fi
CVE-2022-43706 MEDIUM 5.4 UPGRADE Cross-site scripting (XSS) vulnerability in the Web UI of StackStorm versions prior to 3.8.0 allowed logged in
CVE-2021-44657 HIGH 8.8 UPGRADE In StackStorm versions prior to 3.6.0, the jinja interpreter was not run in sandbox mode and thus allows execu

References

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