Withdrawn Advisory: Kirby CMS has Persistent DoS via Malformed Image Upload

CVE-2026-29905 → View on GitHub ↗ View on CVE.org ↗ View on NVD ↗

Description

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This advisory has been withdrawn because it is been determined to not be a vulnerability.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

Basic information

Type
reviewed
Severity
medium
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2026-03-27 22:21:26 UTC
Updated
2026-04-30 18:33:04 UTC
GitHub reviewed
2026-03-27 22:21:26 UTC
NVD published
2026-03-26
Withdrawn
2026-04-30 18:33:03 UTC

EPSS Score

Score Percentile
0.04% 13.31%

CVSS Scores

Base score Version Severity Vector
6.5 3.1 —
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.

Identifiers

Type Value
GHSA GHSA-cw7v-45wm-mcf2 ↗
CVE CVE-2026-29905 ↗

CWEs

CWE id Name
CWE-20 Improper Input Validation
CWE-252 Unchecked Return Value

Credits

  • 0x5t4l1n (finder)
  • lukasbestle (analyst)

Affected packages (1)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
composer getkirby/cms < 5.2.0-rc.1 5.2.0-rc.1 —

References

cvelogic Threat Intelligence