What’s Vulnerable › Vulnerabilities

CVE-2026-71415: Kirby: File upload permissions are not checked during processing of chunk data

• Severity: high (CVSS 7.1 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-31 · updated 2026-09-08
• Weakness: CWE-862

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 products

• getkirby kirby: from 5.0.0, < 5.5.2

References

• https://github.com/getkirby/kirby/commit/37e206f3ed40ad3fab2e47e055ccb19e9c207dab
• https://github.com/getkirby/kirby/pull/8296
• https://github.com/getkirby/kirby/releases/tag/5.5.2
• https://github.com/getkirby/kirby/security/advisories/GHSA-67mx-6wf2-92xp

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