What is the CVSS score of CVE-2026-21896?

CVE-2026-21896 has a CVSS 3.1 base score of 5.7 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N. EPSS exploitation probability: 0.0%.

Which versions of Kirby are affected by CVE-2026-21896?

Organizations using Kirby should be aware of moderate risk from CVE-2026-21896, a incorrect authorization vulnerability rated CVSS 5.7. Attackers could gain access beyond their authorized level.. A patch is available.

Kirby CVE-2026-21896

MEDIUM

Incorrect Authorization (CWE-863)

2026-01-08 security-advisories@github.com

GHSA-4j78-4xrm-cr2f

Authentication Bypass Kirby

5.7

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

5.7 MEDIUM

AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:54 vuln.today

Patch released

Feb 02, 2026 - 19:02 nvd

Patch available

CVE Published

Jan 08, 2026 - 18:15 nvd

MEDIUM 5.7

DescriptionGitHub Advisory

Kirby is an open-source content management system. From versions 5.0.0 to 5.2.1, Kirby is missing permission checks in the content changes API. This vulnerability affects all Kirby sites where user permissions are configured to prevent specific role(s) from performing write actions, specifically by disabling the update permission with the intent to prevent modifications to site content. This vulnerability does not affect those who have not altered the deviated from default user permissions. This issue has been patched in version 5.2.2.

AnalysisAI

Kirby CMS versions 5.0.0-5.2.1 fail to enforce permission checks in the content changes API, allowing authenticated users with restricted roles to modify site content despite having update permissions disabled. This affects only installations with custom permission configurations designed to prevent write access for specific user roles. …

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Vulnerability AssessmentAI

Risk Assessment	CVSS 5.7 (MEDIUM). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario	An attacker could exploit this vulnerability to compromise the affected system.
Remediation	A vendor patch is available — apply it immediately. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. …

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CVE-2026-21896 vulnerability details – vuln.today

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