CVE-2026-71415

Kirby: File upload permissions are not checked during processing of chunk data

HIGH
7.1
CVSS Score
Published: August 31, 2026 at 08:46 PM UTC
Updated: September 8, 2026 at 09:29 PM UTC
1 product affected across 1 vendorKirby

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Severity
HIGH7.1
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

Description

Kirby is an open-source content management system. From 5.0.0 until 5.5.2, Kirby's REST API chunk upload handler in src/Api/Upload.php did not run the relevant upload authorization preflight in Kirby\Api\Upload::process() before Kirby\Api\Upload::processChunk() persisted chunk data. An authenticated user with the access.panel permission enabled but with files.create, files.replace, and user/users.update permissions disabled could submit requests with an Upload-Length header and leave unfinished chunks in site/cache/.uploads for 24 hours. Repeating this process could consume attacker-controlled temporary storage, prevent other users from uploading files, or prevent site logic from storing data, although final permission checks still prevented unauthorized files from reaching the content or site/accounts directories. This issue is fixed in version 5.5.2.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

60%
v < 5.5.2
Affected range stops below 5.5.2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.1HIGHGitHub_M
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-862

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