CVE-2026-23891: Decidim has a cross-site scripting (XSS) in user name
Impact A stored code execution vulnerability in the user name field allows a low-privileged attacker to execute arbitrary code in the context of any user who passively visits a comment page, resulting in high confidentiality and integrity impact across security boundaries.
Published Apr 13, 2026 · Updated May 13, 2026
Affected packages
decidim-core
- Ecosystem
- RubyGems
- Affected
- >= 0.31.0.rc1, < 0.31.0
- Fixed in
- 0.31.1
- Check
bundle info decidim-core
decidim-core
- Ecosystem
- RubyGems
- Affected
- < 0.30.5
- Fixed in
- 0.30.5
- Check
bundle info decidim-core
Advisory details
From the GitHub Advisory Database (CC BY 4.0).
Impact
A stored code execution vulnerability in the user name field allows a low-privileged attacker to execute arbitrary code in the context of any user who passively visits a comment page, resulting in high confidentiality and integrity impact across security boundaries.
Patches
N/A
Workarounds
Not available
References
OWASP ASVS v4.0.3-5.1.3
Credits
This issue was discovered in a security audit organized by octree and made by Secu Labs against Decidim financed by the city of Lausanne (Switzerland).
Credited to cyberschnaps.
References
- https://github.com/decidim/decidim/security/advisories/GHSA-fc46-r95f-hq7g
- https://github.com/decidim/decidim/releases/tag/v0.30.5
- https://github.com/decidim/decidim/releases/tag/v0.31.1
- https://nvd.nist.gov/vuln/detail/CVE-2026-23891
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/decidim-core/CVE-2026-23891.yml
- https://github.com/advisories/GHSA-fc46-r95f-hq7g
How this page is made: the data panel comes from the GitHub Advisory Database, CISA’s KEV catalog, the NVD and FIRST EPSS, and updates twice a day. No analysis has been written for this entry yet. Methodology