StackStorm st2 Infinite Loop Condition

published 2021-03-18 5y ago modified 2026-09-10 last mo. also GHSA-39mj-fpg2-3jrg , EUVD-2022-2150

cvss: 7.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 2.5%; EPSS 2.5% chance of exploitation in 30 days, percentile 84%
public exploits: 0; none known

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).

Patch / fix

fixed in 1 links 1

stackstorm stackstorm 3.4.1

stackstorm.com/2021/03/10/stackstorm-v3-4-1-security-fix/ advisory

Is CVE-2021-28667 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

2.48% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
NVD	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD	2.0	7.1	AV:N/AC:M/Au:N/C:N/I:N/A:C

Classification

Weakness

CWE-835 Loop with Unreachable Exit Condition

References

stackstorm.com /2021/03/10/stackstorm-v3-4-1-security-fix/
patch, vendor-advisory
nvd.nist.gov /vuln/detail/CVE-2021-28667
advisory
github.com /StackStorm/st2
package
stackstorm.com /2021/03/10/stackstorm-v3-4-1-security-fix
web

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.