DecidimApplication
CVE-2026-23891
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedDecidim is a participatory democracy framework. In versions below 0.30.5 and 0.31.0.rc1 through 0.31.0, 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. This issue has been fixed in versions 0.30.5 and 0.31.1.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA stored code execution vulnerability exists in Decidim's user name field. Low-privileged attackers can inject malicious scripts into their username, which executes in the browser context of any user who views a comment page where that username is displayed, leading to arbitrary code execution.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
DecidimApplication
< 0.30.5>= 0.31.0, < 0.31.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- Required
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify Decidim installation versionLocate the Decidim version file or check the Gemfile.lock in your Decidim deployment directory for the decidim gem version entryAffected if The version shown is less than 0.30.5, or greater than or equal to 0.31.0 but less than 0.31.1
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Verify the comment feature is enabledCheck if your Decidim instance has comments functionality active by accessing any resource that supports comments or reviewing your module configurationAffected if Comments are enabled and publicly accessible
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Inspect user accounts for suspicious username patternsReview the users table or user administration interface for usernames containing script tags, javascript: prefixes, or unusual HTML characters that may indicate injected payloadsAffected if Any user account displays a username with unescaped HTML or script content when viewed on comment pages
You are affected if your Decidim version is below 0.30.5 or falls between 0.31.0 and 0.31.1 inclusive, and the comment feature is active where user usernames are rendered.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped0.30.50.31.1
Upgrade Decidim to version 0.30.5 or 0.31.1 to patch the vulnerability.
Upgrade to Decidim 0.30.5 or 0.31.1 (depending on your current major version)
- 1. Back up your current Decidim installation and database before upgrading.
- 2. If you are currently on a version < 0.30.5, upgrade to version 0.30.5.
- 3. If you are currently on version 0.31.0.x, upgrade to version 0.31.1.
- 4. Verify the upgrade by checking that the application runs without errors.
- 5. Test that user name field input is properly sanitized on comment pages.
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Decidim
Scoped from the published advisory
- Consultation4.0 h
- Implementation2.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,928.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-23891 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-23891 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data