High severity · published Aug 18, 2026
CVE-2026-55839
Kestra: Stored XSS via custom Markdown [[link]] attribute injection
8.7
CVSS
0.4%
EPSS
No
On KEV
Description
Kestra is an open-source, event-driven orchestration platform. Prior to 1.3.24, Kestra's custom Markdown parser in ui/src/utils/markdown_plugins/link.ts allows a user with permission to create or update a Flow description to inject JavaScript event-handler attributes through the custom [[link]] syntax, causing stored cross-site scripting when another user opens the description or information panel in the Flow list. This issue is fixed in version 1.3.24.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
Required
Confidentiality
High
Integrity
High
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 37% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
KE
kestra · kestra-io
< 1.3.24 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-55839
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-55839
github.com
https://github.com/kestra-io/kestra/commit/6c8e6d099ed172cbb6b003b7fb30b7bb1f8f710e
github.com
https://github.com/kestra-io/kestra/pull/16835
github.com
https://github.com/kestra-io/kestra/releases/tag/v1.3.24
github.com
https://github.com/kestra-io/kestra/security/advisories/GHSA-34pm-923j-7wf8
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