CVE-2026-29905: Withdrawn Advisory Denial of Service Vulnerability

MODERATE
Advisory Identifier: GHSA-cw7v-45wm-mcf2
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CVSS 6.5
CWE-252 CWE-20
Published
Advisory Summary

CVE-2026-29905 is a MODERATE (CVSS 6.5) denial of service vulnerability (CWE-252: Unchecked Return Value) affecting Withdrawn Advisory libraries in the Packagist ecosystem. The issue involves kirby cms has persistent dos via malformed image upload. Remediation is available by upgrading affected packages to version 5.2.0-rc.1.

CVE-2026-29905 at a Glance

CVE Identifier CVE-2026-29905
GHSA Identifier GHSA-cw7v-45wm-mcf2
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-252: Unchecked Return Value
Affected Product Withdrawn Advisory
Package Ecosystem Packagist
Published Date
Last Updated

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-29905

To remediate this vulnerability, upgrade all affected Withdrawn Advisory dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

getkirby/cms fixed: 5.2.0-rc.1 
Upgrade getkirby/cms to 5.2.0-rc.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for getkirby/cms

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-29905, inspect your project dependencies for Withdrawn Advisory:

inspect dependencies for getkirby/cms

Analyze the terminal output to locate any version of Withdrawn Advisory in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.2.0-rc.1), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-252: Unchecked Return Value, where the product does not check the return value from a method or function, which can prevent it from detecting unexpected states and conditions. In Withdrawn Advisory, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Duplicate Advisory This advisory has been withdrawn because it is been determined to not be a vulnerability. This link is maintained to preserve external references. ### Original Description ## Summary Kirby CMS through version 5.1.4 allows an authenticated user with Editor permissions to cause a persistent Denial of Service (DoS) via a malformed image upload. ## Details The vulnerability is caused by improper validation of the return value of PHP's `getimagesize()` function. When a malformed file is uploaded with a valid image extension (e.g., `.jpg`), the function returns `false` instead of an expected array. The application fails to handle this condition properly and proceeds with image processing, resulting in a fatal `TypeError`. This leads to persistent application crashes when the affected file is accessed. ## Impact - Persistent Denial of Service (DoS) - Affected pages return HTTP 500 errors - Requires manual removal of the malformed file to restore functionality - Exploitable by authenticated users with Editor permissions ## Identifiers - CVE-2026-29905 ## Resources - https://github.com/github/advisory-database/pull/7503 - https://github.com/Stalin-143/CVE-2026-29905 - https://github.com/getkirby/kirby/releases/tag/5.2.0-rc.1 - https://www.cve.org/CVERecord?id=CVE-2026-29905

CVE-2026-29905 Affected Withdrawn Advisory Versions

1 component(s)
Fixed Versions:
5.2.0-rc.1
Product / Package Ecosystem Affected Versions Fixed Version
getkirby/cms
 Packagist
< 5.2.0-rc.1
5.2.0-rc.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/Stalin-143/CVE-2026-29905/security/advisories/GHSA-cw7v-45wm-mcf2
NVD — CVE-2026-29905 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-29905
Withdrawn Advisory Source Repository REPOSITORY
https://github.com/github/advisory-database/pull/7503
drive.google.com/file/d/1mwvvsyiwnc8... WEB
https://drive.google.com/file/d/1MwvvSYIwnC8kOIzjycGMQZw4d2K2ef8h/view?usp=sharing
Withdrawn Advisory Source Repository REPOSITORY
https://github.com/Stalin-143/CVE-2026-29905
Withdrawn Advisory Release RELEASE
https://github.com/getkirby/kirby/releases/tag/5.2.0-rc.1

Frequently Asked Questions

What is CVE-2026-29905?
CVE-2026-29905 is a security vulnerability in Withdrawn Advisory involving Kirby CMS has Persistent DoS via Malformed Image Upload under CWE-252: Unchecked Return Value.
Which Withdrawn Advisory versions are affected?
Affected versions include releases prior to 5.2.0-rc.1 across affected packages: getkirby/cms.
What version fixes CVE-2026-29905?
Upgrading to 5.2.0-rc.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is getkirby/cms affected?
Yes, getkirby/cms is affected in releases prior to 5.2.0-rc.1. Upgrade your dependency to 5.2.0-rc.1 or later.
What is the CVSS score of CVE-2026-29905?
CVE-2026-29905 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-29905?
CVE-2026-29905 is classified under CWE-252: Unchecked Return Value (The product does not check the return value from a method or function, which can prevent it from detecting unexpected states and conditions.).
How can I check Packagist dependencies for CVE-2026-29905?
Run the dependency tree command: 'inspect dependencies for getkirby/cms'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-cw7v-45wm-mcf2",
  "modified" : "2026-04-30T18:33:03Z",
  "published" : "2026-03-27T22:21:26Z",
  "withdrawn" : "2026-04-30T18:33:03Z",
  "aliases" : [ "CVE-2026-29905" ],
  "summary" : "Withdrawn Advisory: Kirby CMS has Persistent DoS via Malformed Image Upload",
  "details" : "### Duplicate Advisory\nThis advisory has been withdrawn because it is been determined to not be a vulnerability. This link is maintained to preserve external references.\n\n### Original Description\n\n## Summary\n\nKirby CMS through version 5.1.4 allows an authenticated user with Editor permissions to cause a persistent Denial of Service (DoS) via a malformed image upload.\n\n## Details\n\nThe vulnerability is caused by improper validation of the return value of PHP's `getimagesize()` function. When a malformed file is uploaded with a valid image extension (e.g., `.jpg`), the function returns `false` instead of an expected array.\n\nThe application fails to handle this condition properly and proceeds with image processing, resulting in a fatal `TypeError`. This leads to persistent application crashes when the affected file is accessed.\n\n## Impact\n\n- Persistent Denial of Service (DoS)\n- Affected pages return HTTP 500 errors\n- Requires manual removal of the malformed file to restore functionality\n- Exploitable by authenticated users with Editor permissions\n\n\n## Identifiers\n- CVE-2026-29905\n\n## Resources\n\n- https://github.com/github/advisory-database/pull/7503\n- https://github.com/Stalin-143/CVE-2026-29905\n- https://github.com/getkirby/kirby/releases/tag/5.2.0-rc.1\n- https://www.cve.org/CVERecord?id=CVE-2026-29905",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Packagist",
      "name" : "getkirby/cms"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "5.2.0-rc.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/Stalin-143/CVE-2026-29905/security/advisories/GHSA-cw7v-45wm-mcf2"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-29905"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/github/advisory-database/pull/7503"
  }, {
    "type" : "WEB",
    "url" : "https://drive.google.com/file/d/1MwvvSYIwnC8kOIzjycGMQZw4d2K2ef8h/view?usp=sharing"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/Stalin-143/CVE-2026-29905"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/getkirby/kirby/releases/tag/5.2.0-rc.1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20", "CWE-252" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-27T22:21:26Z",
    "nvd_published_at" : "2026-03-26T17:16:34Z"
  }
}