TryGhost up to 6.21.0 incomplete blacklist

Summaryinfo

A vulnerability was found in TryGhost Ghost up to 6.21.0. It has been classified as critical. The affected element is an unknown function. The manipulation leads to incomplete blacklist. This vulnerability is documented as CVE-2026-53944. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as critical, has been found in TryGhost Ghost up to 6.21.0. This issue affects an unknown code block. The manipulation with an unknown input leads to a incomplete blacklist vulnerability. Using CWE to declare the problem leads to CWE-184. The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are not allowed by policy or otherwise require other action to neutralize before additional processing takes place, but the list is incomplete, leading to resultant weaknesses. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Ghost is a Node.js content management system. From 6.0.9 until 6.21.1, when making an external request, it is possible to bypass the IP filter that ensures the request isn't going to an internal service using an IPv6 literal which maps to a private IPv4 address. This vulnerability is fixed in 6.21.1.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-53944 since 06/11/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1562.006 according to MITRE ATT&CK.

Upgrading to version 6.21.1 eliminates this vulnerability.

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Productinfo

Vendor

• TryGhost

Name

• Ghost

Version

• 6.0
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6
• 6.7
• 6.8
• 6.9
• 6.10
• 6.11
• 6.12
• 6.13
• 6.14
• 6.15
• 6.16
• 6.17
• 6.18
• 6.19
• 6.20
• 6.21.0

Website

• Product: https://github.com/TryGhost/Ghost/

CPE 2.3info

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Entryinfo

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